Alex Oxlade-Chamberlain will miss up to seven weeks of Arsenal’s Premier League title challenge as a result of the “quite serious” knee injury.

Arsene Wenger suggested that the injury did not appear severe enough to rule the midfielder out of this summer’s European Championship but admitted that club and country were waiting anxiously on the results of a scan. 

Oxlade-Chamberlain sustained the injury in a tackle by Javier Mascherano.

“It is a new injury,” said Wenger. “When he has been cut in two by Mascherano he did his knee. We have to see how big the damage is. I don’t think it was a malicious tackle, it was a fully committed tackle. Let’s hope we get good news that [Oxlade-Chamberlain’s absence] is only two to three weeks and not six to seven.”

David de Gea escaped serious injury when he hurt his knee ahead of Manchester United's Europa League match last week.

De Gea had been withdrawn from his team's 2-1 defeat in the first leg of that Europa League contest after feeling the problem during the warm-up to the game.

The incident at Midtjylland had occurred while De Gea was making what looked like a routine save, then he went back into the dressing room for treatment. 

David de Gea was injured in warm-ups before Manchester United played its Europa League tie against Midtjylland.

De Gea reportedly hurt an ankle and Sergio Romero was in their starting XI in his place.

De Gea becomes the 11th United player out because of injury.

Wayne Rooney will miss up to two months with knee ligament damage.

Rooney played all of Saturday's 2-1 defeat at Sunderland and showed no signs of being injured.

United are also without Matteo Darmian for the trip to the MCH Arena so Donald Love, the 21-year-old full-back who replaced the Italian at Sunderland and made his senior debut, has been chosen.

The inexperienced Will Keane, 23, Regan Poole, 17, Joe Riley, 19, and James Weir, 21, are also in the squad.

Diego Costa suffered a broken nose in training and will wear a mask moving forward.

Costa is Chelsea's only fully fit striker as Loic Remy battles a calf issue and Radamel Falcao is a long-term absentee with a thigh injury.

Costa had a freak collision with academy player Fikayo Tomori during Thursday's training session.

"Diego got his nose broken in a duel," Hiddink explained. "It was one of the youngsters of the academy that we like to participate in our sessions. It was not a tough duel but he put his nose on the back of the head [of the other player] in the duel. He was very unlucky and his nose was broken.

"He will return [on Friday afternoon] because we will give him a mask. We're a team with a lot of masks -- a Zorro team! Azpi [Cesar Azpilicueta], [Nemanja] Matic, now Diego. He will come back and do some light training in the afternoon because he must also know how he's dealing with the form and fitting of the mask. Then he will come back to the hotel later.

"It was a very small incident, a duel, nothing, but it's very fragile when you put your nose on the back of the head of a very young man. I think he will be available. We'll see how he will react to a very light session this afternoon. I hope, I'm not sure but I think he will be."

Kurt Zouma will miss at least six months with a torn ACL in his right knee.

Zouma leapt beyond Marouane Fellaini and his right leg buckled grotesquely as he landed.

Juan Mata led the appeals for a medical staff to immediately come onto the field.

Zouma will miss Euro 2016 for France and the rest of Chelsea's season.

“Scan today has shown I injured my ACL,” said Zouma on his Twitter feed. “I will have surgery this week and will come back stronger.” 

Lionel Messi will undergo a medical procedure for kidney stones but is not expected to miss Barcelona's match against Valencia.

Messi didn't train on Monday.

According to Mundo Deportivo, the Argentina international will be treated at the Dexeus university hospital in Barcelona, where he will receive shock wave lithotripsy, a non-invasive treatment common in the United States that breaks up the stones into tiny pieces.