Manchester United's progress to the Europa League quarterfinals came at a cost after Paul Pogba hobbled off with a hamstring injury in the 1-0 win over Rostov on Thursday.
United manager Jose Mourinho suggested Pogba "paid a price" for the team's accumulation of fixtures as the world's most expensive player pulled up in the 47th minute at Old Trafford and slumped to the ground.
The English club ended up stumbling through to the last eight, with Juan Mata's 70th-minute goal winning the second leg and clinching a 2-1 victory on aggregate.
United will be the standout team in the draw for the quarterfinals in Nyon on Friday, with Lyon potentially the biggest rival.
The French side lost 2-1 at Roma but went through 5-4 on aggregate because of its big win at home last week. There looks to be good depth in French soccer at present, with Monaco qualifying for the Champions League quarterfinals and Paris Saint-Germain missing out only because of a sensational second-leg fightback in the last 16.
Mouctar Diakhaby put Lyon ahead in the 16th before Roma fought back through Kevin Strootman's strike and Lucas Tousard's own goal.
Compared to recent years, Europe's second-tier competition is shorn of genuine quality.
United will be the favorite and is taking the competition seriously as it offers a route into the Champions League. United is sixth in the English Premier League, with only the top four securing Champions League qualification.
Fatigue might prove to be a factor for Mourinho's side, though.
Injuries are mounting, with Daley Blind joining Pogba in going off early in the second half and Marcos Rojo playing on through injury to the final whistle. In a bid to give Rojo some energy, Mourinho sent a banana onto the field for the defender to eat.
Having played away to Chelsea in the FA Cup on Monday night, United faces a Premier League match at Middlesbrough on Sunday lunchtime. That will be United's fifth game in 16 days.
"We have a lot of enemies," Mourinho said. "A lot of people might say we should have scored more goals. But a lot of things are going against us."
Here's a look at other second legs:
BORUSSIA MOENCHENGLADBACH 2, SCHALKE 2 (3-3 aggregate, Schalke advances on away goals)
This all-German matchup was the only last-16 contest to be settled by the away-goals rule.
Midfielder Nabil Bentaleb scored the decisive goal with a 68th-minute penalty, as Schalke came from two goals behind on the night.
Andreas Christiansen and Mahmoud Dahoud put Moenchengladbach 3-1 ahead on aggregate, but Dahoud conceded the penalty with a handball.
AJAX 2, COPENHAGEN 0 (Ajax advances 3-2 on aggregate)
Ajax overturned a 2-1 deficit from the first leg thanks to first-half goals by Bertrand Traore and Kasper Dolberg.
Dolberg converted the crucial goal from the penalty spot in the third minute of stoppage time after he was tripped in the area.
BESIKTAS 4, OLYMPIAKOS 1 (Besiktas advances 5-2 on aggregate)
Besiktas weathered the first-half sending-off of Vincent Aboubakar to advance to the quarterfinals for the second time.
Aboubakar opened the scoring for the Turkish champions long before he was given a straight red card for an off-the-ball incident in the 39th.
At that stage, Besiktas was 2-1 ahead on the night — and 3-2 up on aggregate — but the hosts scored in the final 15 minutes through Ryan Babel and Cenk Tosun to ease through.
KRASNODAR 0, CELTA VIGO 2 (Celta Vigo advances 4-1 on aggregate)
Celta Vigo is back in the last eight for the first time in 16 years.
Second-half goals from Mallo and Iago Aspas allowed Celta to build on its 2-1 lead from the first leg.
Celta is the only Spanish team remaining. Spain has had five winners in the last seven Europa Leagues.
There will be two Belgian teams in the quarterfinals.
Genk overcame Gent 6-3 on aggregate in their all-Belgian matchup after a 1-1 draw in the second leg, while Anderlecht earned a second 1-0 win over APOEL thanks to Frank Acheampomng's goal.