Manchester United captain Harry Maguire has one big concern ahead of the Chelsea clash.
The two teams meet at Stamford Bridge on Monday night in the reverse fixture from the opening weekend of the new Premier League season - a game which the Red Devils won 4-0 to ruin Frank Lampard's debut as Blues head coach.
That game at Old Trafford also marked Maguire's first start in United colours following his £80m transfer from Leicester City - a world record fee for a defender.
His central defensive partner that afternoon was Victor Lindelof and the duo have been Ole Gunnar Solskjaer's first-choice defensive pairing this season and are likely to start again in west London.
Speaking ahead of the big game, Maguire has said that he is pleased with how his partnership with the Sweden international has gone and thinks there's a lot more to come.
However, he also highlighted United's biggest defensive weakness which could play into Chelsea's hands and deal Solskjaer a blow in the top-four race.
"It's been brilliant [playing with Victor]," Maguire told ManUtd.com. "We've had a good season up to now together. When you form partnerships, it takes time.
"I'm learning his game and he's learning mine and I think we're getting better.
"We're keeping a lot more clean sheets than we were at the start of season and we've never really been a team which has conceded a lot of chances.
"We've been poor from set-plays with our defending and we've had a couple of great goals scored against us from outside the box, but we haven’t really been having games where David [De Gea] has had to make five or six saves, apart from maybe the Carabao Cup second leg against [Manchester] City, when David was brilliant.
"It's a partnership that's building and I think we'll get better and better, and start keeping more clean sheets like we have been doing recently."
Maguire's admission about United's struggles from set-pieces could be where the game is won or lost on Monday night.
Arsenal and Liverpool have benefited from this already in 2020 and United have conceded 10 goals from set-pieces this season (via whoscored) only Aston Villa and Everton have conceded more across the entire division.
Interestingly, Chelsea have scored eight goals from set-pieces this season and two of them came via Antonio Rudiger's head in the 2-2 draw against Leicester City before the winter break.
