De Gea sucked the life out of United's Champions League campaign when he let a comfortable right-footed Lionel Messi shot to dribble past him at the Nou Camp.
Bailly left the stadium on crutches and wearing a leg brace and is unlikely to play again until next season.
Chelsea's N'Golo Kante has scored nine goals in all competitions in his four seasons in England, with Manchester United the only side he's scored a few times against (2).
The United manager has Argentina No. 1 Sergio Romero to turn to but suggested De Gea would keep the gloves at the John Smith's Stadium.
The Blues take the trip to Old Trafford on Sunday in what could prove to be a hugely significant game for themselves and Manchester United, as the race for top four enters the final few weeks of the season. After playing out to a draw against Burnley during their last game, the Blues next take on Manchester United.
Arsenal manager Unai Emery has explained the reason behind the absence of star striker Pierre-Emerick Aubameyang for the Premier League clash with Wolverhampton Wanderers on Wednesday night.
"We have to play against opponents with a very high level of motivation after the Manchester derby".
"Tactically, we are improving", he said.
"We do support each other and there's no chance anyone can blame him for losing many points for us". He knows he could have had that shot but that is football.
The goal came just before half-time, levelling the scoreboard following Juan Mata's 11th minute opener and very much sucking the wind out of an expectant home fanbase who are now experiencing their sides's worst form in decades and Manchester United's recent slide in results coincides with the poorest form of De Gea's Old Trafford career.
"David knows he could have done better with the goal, there's no reason hiding that".
For so long, he was the only player whose place in the team was not under scrutiny.
Chelsea haven't gone three Premier League games without a win since September 2016.
Chelsea have won more Premier League games against United than any other side have in the competition (18).
It was United who created the first clear chance of the half when Rojo jumped to meet a corner but his header was cleared off the line by Pedro, while De Gea at least ended the game well with a block from Gonzalo Higuain.
It is believed that Sarri's coaching staff are convinced he will be sacked at the end of the season as the Italian has been linked with a move back to Serie A to join either one of AC Milan, Inter Milan or Roma.
