Erik ten Hag saluted Luke Shaw's "fabulous" performances at centre-half in Manchester United's victories over Nottingham Forest and Wolves.
The Dutchman has been forced to rotate United's defence on their return to action with Harry Maguire and Victor Lindelof suffering from illness and Lisandro Martinez still regaining fitness after Argentina's World Cup glory.
Casemiro filled in at centre-half during the EFL Cup victory over Burnley, while Shaw played alongside Raphael Varane in the heart of defence for their Premier League outings against Forest and Wolves.
Ten Hag's decision was justified with United recording consecutive clean sheets, and the England full-back could continue in the unfamiliar role for the visit of Bournemouth on Tuesday.
Explaining his thinking, the manager said of Shaw: "We have seen the last two games. I think he did fabulous and was impressing. We know also he is really good as a left full-back, but it's an extra option and [that] is always good for a team.
"Of course, you have your ideas and a plan, but sometimes it changes by circumstances like illnesses from Harry [Maguire] and from Victor [Lindelof].
"Normally, they should have started in the games we just played, but then Casemiro did well as a centre-half, Luke Shaw against Forest did very good, and also you look into the game plan, the way we have to approach Wolves.
"And I thought it was the best match with Rapha and Luke. Especially defending wise, we know the speed from Wolves over on the right side.
"[Shaw] could cover that because we want to attack over on the left side with offensive game from Tyrell Malacia, so that was a good fit. And also in possession, you always – with a left foot – get better angles on the pitch."
Ten Hag also revealed Martinez and Scott McTominay could return for the hosts in the first of four successive fixtures at Old Trafford, while Diogo Dalot could be in contention to feature as well.
"We have to see," he added. "Both [Martinez and McTominay] were training yesterday and today, so I am quite optimistic about [them] returning to the squad, both of them.
"Diogo Dalot also, he is making good progress – but we don't want to take risks with anyone because we know there are many games to come, and we need a full squad to cover all the games."