Antonio Conte believes Tottenham need to delve into the transfer market if they are to repeat their "miracle" top-four finish of last season.
Spurs finished the 2021-22 campaign strongly to pip rivals Arsenal to Champions League qualification, but their attempts to finish in the top four again this season have faltered.
A 2-0 home defeat to Aston Villa on Sunday, as well as a draw with Brentford on Boxing Day, means Spurs have lost ground on Manchester United, with the Red Devils making it three straight wins with victory over Wolves on Saturday to move into fourth.
Conte's side have been unfortunate with injuries, with key players such as Dejan Kulusevski and Richarlison both spending time on the sidelines.
Former Chelsea and Inter boss Conte feels Spurs could do with signing players to build the depth of their squad and make them competitive at the top end of the Premier League.
"I continue to repeat that we made a miracle [finishing fourth last season]," he told reporters after goals from Emiliano Buendia and Douglas Luiz condemned his side to defeat.
"Because we played only one competition with 12, 13 players and they didn't have injuries in the last 15 games and we played only the best players. Arsenal were only four points up and we finished 20 points less than Manchester City. We did a miracle and I knew the situation.
"I was very clear with the club and in the summer people spoke about Tottenham as title contenders. From my experience it was a bit crazy to read this but you have to accept this. If you have these injuries it becomes difficult.
"To become title contenders you need a solid foundation, 14, 15 strong quality players and the young players to develop and every season you can add two players, two players to invest £60million, £70m players to improve the level of your team."
Despite the Villa defeat, Conte was pleased with his side's attitude and he is confident his team will bounce back when they take on Crystal Palace at Selhurst Park on Wednesday.
"About the performance, I'm not disappointed," Conte said. "From the start to the end I've seen the right commitment and desire and intensity.
"I was expecting this moment. Now we have to fight, strong, because the situation, we are there and in this league you can slip quickly.
"I'm not scared. I believe in my work and I believe in these players."