Manchester United boss Erik ten Hag is expecting a "difficult" test against Aston Villa following the appointment of Unai Emery, who has his first game in charge on Sunday.
The Spaniard makes his return to the Premier League after a previous stint with Arsenal, having rebuilt his reputation with Villarreal, where he won the Europa League against United in 2020-21.
A swift impact is needed at Villa, who enter the match on the back of a 4-0 drubbing at the hands of Newcastle United last time out and having won just one of their past six Premier League matches.
United, meanwhile, have enjoyed back-to-back 1-0 victories against West Ham and Real Sociedad but will need to make changes amid their packed schedule, with Ten Hag mulling over his defensive options.
"I have to see because Aston Villa is going to be a difficult one as we don't know. They have a new manager and I have to have a look and analyse from that game, from that team and then we have a choice," he said.
"But Lisandro Martinez and Victor Lindelof played really well together over some more games. I also think Licha [Martinez] and Harry [Maguire] last Sunday against West Ham United kept a clean sheet and also did really well.
"So that's a choice we have to make. When I choose one, it is not one thing against the other.''
One definite change will come in midfield due to Bruno Fernandes' suspension, having accrued five yellow cards in the Premier League.
''We know that we have to replace Bruno. That is quite clear," Ten Hag added.
"We have to see how we replace him and we have to think about that and it is short, so soon after this [Real Sociedad] game. I have one night to think about that.''
United travelled to Spain without attacking trio Antony, Jadon Sancho and Anthony Martial, with Ten Hag unsure if they would be available for this weekend's game.
"It's difficult to say in this moment," he said. "I have to talk with the medical and the performance team as they did a programme in Manchester.
"I have to hear how their progress was and if they can be available for Sunday's match."