Jose Mourinho could rest key players for Arsenal game

Three underwhelming years under firstly David Moyes and then Louis van Gaal saw the Old Trafford board turn to the Portuguese last summer.

EFL Cup and Community Shield triumphs in his first campaign have been tempered by Premier League struggles, with Sunday's 1-1 draw against Swansea leaving United in fifth - a point shy of Manchester City with four tough fixtures remaining.

A trip to Arsenal awaits on Sunday and Mourinho could rotate his side given the match comes between European semi-final clashes against Celta Vigo, with Europa League glory offering Champions League qualification and a place in the history books.

Only Ajax, Bayern Munich and Juventus have won all three major UEFA trophies, including the now-defunct European Cup Winners' Cup, as well as the Club World Cup or the Intercontinental Cup.

United never tasted trophy success in the UEFA Cup, which evolved to become the Europa League from the 2009/10 season.

Mourinho said ahead of Thursday's first leg against Celta in Spain: "I know that it is the only competition that Manchester United as a club have never won and it would be great to close the circle and say, 'We are a club that won every single competition in the football world'.

"Thinking about us as a team, I think it would be a good achievement with so many problems we have and would allow us to be back to Champions League next season.

"So we have to try, that's what we are going to do, and honestly the Europa League for us now becomes more important.

"Of course it depends on the result, it depends on the way we analyse the situation tomorrow after the match, but if we have to rest players next weekend, we are going to do that."

Had it not been for a lack of cutting edge and a Premier League-high 14 draws, United would not be worrying about a top-four finish.

Mourinho also believes injuries and fatigue have had a lot to do with their struggles, meaning the return of Chris Smalling and Phil Jones after being injured on England duty in March could be too little, too late on the domestic front.

"In relation to the Europa League, it is very important they come in time," Mourinho said, having also confirmed Paul Pogba was back.

"We have two matches in one week against Celta. It is important to have everybody back.

"In relation to the Premier League, I think it is too late because in the past month of April we played nine matches - seven of them in the Premier League and we had too many problems, we had too many players absent.

"Because of that, we had players that had to play 750, 800 minutes of football and we paid the price.

"We played against fresh teams and we were in accumulation (of fatigue).

"At this moment, the perspective is different because the Europa League becomes even more important for us.

"And it is good to have three players back, that gives us more options."

Eric Bailly is also "ready to play" having come off against Swansea, while Marouane Fellaini's ban only affects domestic matches.

Luke Shaw has joined Zlatan Ibrahimovic, Marcos Rojo and Tim Fosu-Mensah in the treatment room, but Juan Mata could make his first appearance in almost seven weeks after recovering from a groin injury.

"Mata was injured for a while but he's ready to play," Mourinho said of the Spaniard, who was on the bench on Sunday.

"He's experienced, he's one of the few players that played European semi-finals and finals, so it's nothing new for him.

"The only risk is he probably can't play 90 minutes, but that's the risk if he starts he doesn't finish the game, if he comes from the bench then it's no problem for him.

"If selected, he can play perfectly tomorrow."

Mata and fellow Spanish midfielder Ander Herrera have warned of the threat posed by Celta, despite the side 11th in LaLiga losing three straight matches.

Much of that is down to rotation with their first major European semi-final looming large and Mourinho knows a tough night lies ahead at Balaidos.

"Celta for some reason is here," the United boss said. "It is as simple as that.

"To win a competition with so many teams with very good balance - almost every team in the knockout phases were teams of the same level - they managed to be in the semi-final. I think it says everything.

"Because of their situation in LaLiga, their situation is comfortable. They manage also to think just about the Europa League, to rest players, to be at the maximum of their condition, so it is a difficult match for us."