Cristiano Ronaldo returning to Manchester United will help Ole Gunnar Solskjaer's side mount a title challenge, according to former Red Devil Wayne Rooney.

Rooney played with Ronaldo during a five-year spell at Old Trafford, winning three Premier League crowns and the Champions League.

The Portugal captain, who blasted in 118 goals in 292 games across all competitions in his first spell with United, could make his second debut as soon as Saturday against Newcastle United, who are the only club he managed a Premier League hat-trick against during his first term in Manchester.

Now managing Derby County, Rooney said he will not be watching his former team-mate's homecoming but predicts Ronaldo to have an "enormous impact" in his second spell.

"He's one of the best players in the world," Rooney told reporters ahead of Derby's clash with Birmingham City on Friday.

"Cristiano will know himself it's not going to be as simple or straightforward for him as it was in Spain or Italy.

"Cristiano's going to be a very big player, I think he's going to have big moments in the season and I'm sure he'll score a lot of goals.

"So I think United are finally ready to go and challenge for the title, and I really feel they have to this year."

Ronaldo missed a 3-0 victory over Azerbaijan with Portugal after being suspended following a caution against the Republic of Ireland for his last-minute goal celebration.

Indeed, in that game the 36-year-old broke Ali Daei's all-time men's international scoring record as he netted his 110th and 111th goals for the Selecao.

And Rooney pointed to that performance as a reason why his former colleague will thrive in the Premier League.

"We saw, in the game against Ireland, what he does," Rooney continued.

"[In the] last couple of minutes, he scores a couple of goals, great headers, so he can have a massive impact on the Premier League.

"It's a physical league, but he knows that, because he's played in it before, so I'm sure he's prepared and ready to go and score goals again for United."

Facundo Pellistri got the decisive goal as Manchester United began their pre-season preparations with a 2-1 win over Wayne Rooney's Derby County.

United great Rooney took over from Phillip Cocu in November and was managing against his former club for the first time.

It was, understandably, an unfamiliar-looking United side, however. With numerous players yet to return after Euro 2020 and the Copa America, and several set to feature at the Olympics, Ole Gunnar Solskjaer was without 16 players.

As such, Tom Heaton started in goal following his return to the club, and he made an important save from point-blank range just before the end of a first half that was made to look like something of a struggle due to the heat.

Nevertheless, United held a 1-0 lead at the interval as Tahith Chong – who is set to go on loan to Derby's Championship rivals Birmingham City – seized on a defensive error and bundled in from close range after seeing his initial chip attempt blocked back on to him.

Solskjaer made as many as nine changes at the break, with Axel Tuanzebe and Teden Mengi the only players to remain in the team. Jesse Lingard, Andreas Pereira, Nemanja Matic, Lee Grant and Alex Telles were among those to come into the side, with several youngsters also involved.

Two of the young hopefuls combined to put United 2-0 up.

Shola Shoretire – who became United's youngest ever player in European competition back in February – sliced through the defence with a clever throughball and Pellistri coolly rounded the goalkeeper before tucking home.

Colin Kazim-Richards pulled one back for Derby from distance, but Pellistri's well-taken goal was enough to give United a winning start to their pre-season

Wayne Rooney believes Phil Foden and Jack Grealish are too good to be left out of the England starting XI for Euro 2020.

Manchester City youngster Foden starred with a goal and an assist in the 4-1 away win at Premier League champions Liverpool last week.

He is gaining momentum after being handed more opportunities by manager Pep Guardiola.

Grealish, meanwhile, has thrived for Aston Villa this season, establishing himself as one of the Premier League's leading players with six top-flight goals and 10 assists.

Rooney is England's record goalscorer and thinks the form of the two attacking midfielders has become impossible to ignore ahead of the tournament.

"They have to be in the squad and arguably have to play because they are that good," the Derby County boss said about Foden and Grealish.

"Phil Foden has been one of the best players in the league this season, I think Guardiola has managed him really well.

"For Phil, it's about keeping doing what he's doing. He's one of the best players in the league this season.

"Foden is performing excellently — scoring, assisting — and hopefully he can carry that form on with England. He is entertaining to watch. 

"When my lad [Kai] used to go into City, I used to see Phil there.

"I spoke to him a couple of times and I could see he's a very level-headed lad. He was there a lot of the time, but it was just general chat, not me giving him advice.

"There are a few players — not just him. I think Jack Grealish brings something different for the national team."

Foden made his England debut away to Iceland in September but was promptly removed from the squad along with Mason Greenwood for breaking coronavirus protocols.

He responded by scoring a double - his first international goals - in the home match against Iceland in November.

Grealish, meanwhile, has five England caps and manager Gareth Southgate has spoken about the dilemma he faces over whether to play him or Chelsea's Mason Mount.

Alex Ferguson says Wayne Rooney has a "presence about him" and is hopeful the legendary forward will succeed in management after announcing his retirement from playing.

Rooney was officially named as Derby County boss on Friday, two months after replacing Phillip Cocu as interim coach.

The 35-year-old enjoyed an incredible playing career that spanned nearly two decades, during which time he won 16 trophies at Manchester United, the majority of those under Ferguson.

He retires as United and England's all-time leading goalscorer and while Ferguson believes that will be an advantage for Rooney, he warned the former forward results were all that mattered as a coach.

"He is England’s top goalscorer, he is Manchester United’s top goalscorer and he has had a fantastic career as a player and it will give him a starting point," Ferguson said on the 'A Team Talk With Legends' panel on Friday.

"But like anyone else it is a results industry and you need to get results. He will know that better than anyone.

"He has had a good start… and he has knowledge of the game, a presence about him and I hope he does well.

"It is a big step for him. He is quite a wealthy young man now with his career in football, so he probably doesn't need to go into management to look after his family, but he wants to do it and that is important.

"There is no point being a manager because someone asks you to be. He went there as a player-coach, he then become player-manager and now he has the manager's job and that's what he wanted. Hopefully he does well.”

England manager Gareth Southgate was also pleased to see Rooney take the helm at Derby.

Rooney joins former England team-mates Steven Gerrard (Rangers), Frank Lampard (Chelsea) and Scott Parker (Fulham) in management.

"He has had an incredible career. I am pleased we have the likes of Wayne, Steven, Frank and Scott Parker – we don't want too many [Jamie] Carraghers sitting on the sofa because those good football brains are gone from the game," Southgate said.

"What you want from an England perspective is young English managers and ex-players to come in and add to the game and help develop young players.

"Those lads have brilliant experiences and it will be a huge challenge of course, but Wayne loves football, has a fantastic brain for football and I wish I had the chance to manage him five years earlier – not be the one to leave him out of the England squad, I'd rather be the one picking him at his peak."

Wayne Rooney has been appointed the new Derby County manager after impressing as interim boss.

The former Manchester United and England captain has signed a two-and-a-half-year contract with the Championship club.

Rooney, 35, has overseen three wins and four draws in nine games since taking temporary charge back in November after Phillip Cocu was sacked with the Rams bottom of the table. They are now 22nd and only in the relegation zone due to goal difference.

The decision to take over as full-time boss means Rooney has officially brought his illustrious playing career to an end.

"When I first arrived back in the United Kingdom I was completely blown away by the potential of Derby County Football Club," Rooney said in a statement. "The stadium, training ground, the quality of the playing staff and the young players coming through and of course the fan base that has remained loyal and supportive.

"Despite other offers I knew instinctively Derby County was the place for me.

"To be given the opportunity to follow the likes of Brian Clough, Jim Smith, Frank Lampard and Phillip Cocu is such an honour and I can promise everyone in involved in the club and all our fans, my staff and I will leave no stone unturned in achieving the potential I have witnessed over the last 12 months of this historic football club."

Rooney's impressive impact upon results has come despite turmoil around the club, including a wage delay, a protracted takeover by Sheikh Khaled bin Zayed Al Nahyan and a coronavirus outbreak that forced the closure of the training ground.

Derby kept five clean sheets, conceded only four goals and lost just twice in their first nine matches under Rooney. No side conceded fewer goals in that time and only Brentford suffered fewer defeats (zero).

Rooney initially joined Derby in a player-coach role in January 2020 after spending two years in MLS with DC United.

England and Manchester United's all-time record goalscorer played 35 times for the Rams, the last of which was in a 3-0 defeat to Middlesbrough on November 25.

Liam Rosenior, Shay Given and Justin Walker will all stay on in Rooney's backroom team, with Rosenior named assistant manager. Former England boss Steve McClaren will continue as technical director.