Winning the Champions League has never been more important for Manchester United. Just to get a chance to rejoin Europe's elite again.
With United in an unusually low English Premier League position, 11 points from the fourth Champions League place, qualifying for next season's Champions League through the usual domestic route seems unlikely.
"As a group of players we have to take responsibility for our league position," United striker Wayne Rooney said. "We know we're better than that and we haven't performed as well as we can do. It hurts."
So David Moyes' side wants to build a strong first-leg lead at Olympiakos on Tuesday to smooth the passage to the quarterfinals. And beyond, given how essential winning the May final is to the club's pride and global standings.
Here are five things to know about Tuesday's round of 16 game in Greece:
RESPITE IN EUROPE: If only United's European form had been replicated domestically, it wouldn't be so bleak for Moyes during his first season in charge. In the Premier League, United is meekly surrendering the trophy, sitting in sixth place, ahead of Everton only on goal difference and having played an extra game. But United eased through the Champions League group stage with four wins, including an eye-catching 5-0 rout at Bayer Leverkusen, and two draws. Going through as group winner ensured the three-time European champion avoided potentially trickier teams at the start of the knockout phase. "We know Manchester United are not allowed to make any mistakes due to their position in the Premier League and we have to say probably this kind of situation may weigh too much on their players' shoulders," Olympiakos manager Michel said. "It could be an incentive to them or it could be a burden on their shoulders."
CONSTRASTING FORM: While it's miserable for United domestically, Olympiakos is unstoppable, sitting 23 points clear at the top of the Greek Super League. Just nine goals have been conceded in 26 unbeaten games. "Olympiakos came through a difficult group with Benfica, Paris Saint-Germain (and Anderlecht)," Moyes said. "They have a great home record so it will be a difficult night."