Ole Gunnar Solskjaer relishing the prospect of trying to thwart Lionel Messi, but he has injury concerns
Nemanja Matic, Ander Herrera, Eric Bailly and Antonio Valencia were conspicuous by their absence as Manchester United trained on the eve of their Champions League quarter-final first leg against Barcelona.
The quartet all missed last week's Premier League loss at Wolves and were absent at the open section of Tuesday's session at the Aon Training Complex.
Alexis Sanchez was involved as he steps up his return to fitness, but there are questions over Marcus Rashford after the forward started the session doing individual work following an ankle injury.
United boss Ole Gunnar Solskjaer is hopeful Rashford will be available for Wednesday's clash.
He told a pre-match press conference: "He needed the extra warm-up and hopefully he won't get a reaction. He joined parts of it (training) at the end. Let's see tomorrow. Hopefully he'll be ready."
Solskjaer also confirmed Bailly and Valencia will miss out on Wednesday but revealed Matic could be available, while Herrera is likely to miss out.
"We still hope maybe that Nemanja can be ready, Ander is probably out and Eric and Antonio are definitely out," he added.
"Every game is the biggest game. The next one is always the biggest but of course when you get a Barcelona - with the history and traditions of that club, the quality of their team and individuals - we know we need to step up our game.
"We know we need to perform at our best level, which we didn't against PSG in the home game. But I think the outcome of the second leg has given players belief, supporters belief that it is possible against a Barcelona team as well."
Solskjaer acknowledged stopping Barcelona forward Lionel Messi will not be straightforward but said it is not impossible.
"What kind of plan can you have to stop one of the best players in the world? We're looking forward to it and relishing the opportunity but this season we've played against Juventus and (Cristiano) Ronaldo, PSG with (Kylian) Mbappe, we've had (Eden) Hazard.
"(Luis) Suarez as well. Suarez, (Philippe) Coutinho and Messi will keep our defenders on their toes so let's see how we manage tomorrow.
"Messi will be difficult to stop but it's never impossible. It's not like it's Messi against Manchester United. There are so many good players, we can't just focus on one player."
One of the players looking to stop Messi will be United defender Chris Smalling, who said said he is looking forward to the test.
"It's something to relish, I think. This season I've been lucky enough to face Ronaldo and Mbappe and they're all challenges that I definitely relish and I think players at this club relish'" Smallling told the press.
"I say bring it on."
Solskjaer also revealed he expects World Cup winning midfielder Paul Pogba to still be at Old Trafford next season.
He said: "Paul is looking forward to tomorrow. He's a Manchester United player. He's one of our, of course, big performers on the big stage.
"He knows the game against PSG was not his greatest moment so he is only focused on playing well tomorrow against Barcelona and I cannot see him not playing for Man United next season either."