Jose Mourinho believes Manchester United will end up "in trouble" if they continue to fight on all fronts.
Thursday's Europa League last-32 first leg against St Etienne kicks off a frantic 11-day period as the second leg in France comes after an FA Cup tie at Blackburn and is followed by the small matter of the EFL Cup final against Southampton.
There will be little let-up if United emerge victorious from that run of matches as more fixtures would leave them with a bloated, uneven schedule.
Mourinho believes balancing domestic and European exertions will stretch his squad and ultimately hamper their chances of success - not that he will allow his side to take their foot off the gas.
"We cannot choose the competitions at Manchester United," the United boss said on the eve of welcoming St Etienne. "We know that our situation is really complicated.
"We know that the Europa League is also a competition where we play on Thursdays and that makes it even more difficult for us.
"Europa League is not a competition we want to play, but it's a competition we play and we respect it."
"The accumulation of FA Cup, League Cup, match postponements is really hard for us. If we progress in the competitions, we will be in trouble in April and May. But we cannot choose competitions, so we play them to win.
"I think it's also a good way to give the team experience and international experience is always a plus.
"Europa League is not a competition we want to play, but it's a competition we play and we respect it."
Mourinho is desperate to return United to Europe's top table, but believes Champions League qualification through the league will be harder to secure than for others as cup progress will "create many, many problems".
"We know that it's going to be very difficult," the United boss said, with just four points separating his side and second-placed Manchester City.
"We know obviously it can have an impact in the Premier League because we are competing against teams in other circumstances.
"For example, Liverpool play only in the Premier League, Chelsea in the Premier League and the FA Cup. We have still Tottenham in a similar situation as us, but we want to progress. That's the point.
"We prefer difficult but progressing to easy and being knocked out of the competitions. We will go seriously tomorrow and seriously against Blackburn on Sunday."
Luke Shaw will be hoping to be involved at Ewood Park having been overlooked for Thursday's match, raising fresh questions over the Manchester United left-back's future.
A double leg break brought last season to a premature - and horrific - end for the 21-year-old, who has struggled to make his mark under Mourinho.
Niggling injuries on the comeback trail have disrupted his campaign but, despite being fit since mid-January, Shaw has made just one appearance against Wigan in the FA Cup fourth round.
The left-back was not involved in the subsequent three squads and Mourinho confirmed the England international will not feature against St Etienne on Thursday in the Europa League last-32 first leg.
"He's not playing tomorrow," Mourinho said. "Because my team is playing well and I am happy with my back four, and I'm going to repeat (Antonio) Valencia, (Eric) Bailly, (Chris) Smalling, (Daley) Blind."
Provisional squad: De Gea, Romero, Henderson, Darmian, Fosu-Mensah, Valencia, Young, Rojo, Tuanzebe, Smalling, Bailly, Blind, Mata, Fellaini, Schweinsteiger, Herrera, Pogba, Lingard, Martial, Mkhitaryan, Rashford, Ibrahimovic.
