Mesut Ozil scored as Arsenal eased to a 3-0 victory at Swedish minnows Ostersunds in the first leg of their Europa League, last-32 tie on Thursday, while Michy Batshuayi snatched Borussia Dortmund a dramatic win over Atalanta.
Left-back Nacho Monreal put Arsenal into an early lead with his fifth goal of the season, tapping in after home goalkeeper Aly Keita inexplicably let the ball slip from his grasp.
The visitors were also gifted the second goal in the 24th minute as Ostersunds tried to play their way out of their own area, with Henrikh Mkhitaryan latching onto the loose ball and seeing a low cross diverted into his own net by defender Sotirios Papagiannopoulos.
Ostersunds coach Graham Potter, a former defender for Stoke and West Brom in England, made two half-time changes in an attempt to change the flow of the game, but Arsenal all but ended the tie before the hour mark.
Mkhitaryan played in Ozil, who jinked his way through and saw his shot burst through the hands of the hapless Keita and bobble into the net.
Ostersunds were gifted a chance to at least add a memorable goal to their fairytale run, but after Tesfaldet Tekie was brought down by Hector Bellerin, David Ospina saved Tom Pettersson's injury-time penalty.
The comfortable win means that Arsenal manager Arsene Wenger will be able to rest his key players for the second leg at the Emirates in a week's time.
"We did the job well, controlled the ball against a good side," Wenger told BT Sport.
"Overall we played a serious game, so job done. They looked very nervous and we took advantage of it."
Red-hot Batshuayi rescues Dortmund
Batshuayi continued his good form with a late brace as Dortmund fought back to beat Atalanta 3-2 at Signal Iduna Park.
Dortmund forged ahead on the half-hour mark through Andre Schurrle, but Josip Ilicic's quickfire double after half-time put Atalanta ahead.
Dortmund hit back midway through the second period, though, as Batshuayi slammed in his fourth goal in three games for the club since joining on loan from Chelsea in January.
And the Belgian striker pounced in the first minute of added time to give the two-time runners-up a precious lead in the tie.
"The really disappointing thing is we threw away a game that we shouldn't have lost," admitted Atalanta coach Gian Piero Gasperini.
"After cradling the dream of winning, we suffered this disappointment in the final minutes. The second leg will not be easy."
Elsewhere, Atletico Madrid recovered from falling behind early on at FC Copenhagen to cruise to a 4-1 victory.
Saul Niguez, Kevin Gameiro and Antoine Griezmann were all on the scoresheet as Diego Simoene's La Liga title-chasers put one foot into the last 16.
Serie A leaders Napoli have it all to do, though, after Germany international Timo Werner's second-half brace led RB Leipzig to a shock 3-1 win in Italy.
Patrick Cutrone and Fabio Borini scored as AC Milan claimed a 3-0 advantage over Ludogorets Razgrad to take back to the San Siro for the return leg.
"I'm a bit angry, we could do a lot better. Having fast players they put us in trouble," said a surprisingly disgruntled Milan coach Gennaro Gattuso.
Mario Balotelli scored twice, but 10-man Nice blew a two-goal lead to lose 3-2 at home to Lokomotiv Moscow as Manuel Fernandes hit a hat-trick, while Valere Germain struck two goals as Marseille cruised past Braga 3-0.
A 78th-minute winner from Callum McGregor gave former European champions Celtic victory over Zenit St Petersburg at Parkhead, and Lazio were beaten 1-0 by FCSB in Bucharest.
Lyon, semi-finalists last season, impressively saw off Villarreal 3-1 with Nabil Fekir and Memphis Depay both finding the net.