Match ends, Arsenal 4, CSKA Moscow 1.
Arsenal manager Arsene Wenger says his side have done "half a job" after a "spectacular" first-half performance saw the Gunners take control of their Europa League quarter-final by demolishing CSKA Moscow in the first leg.
Alexandre Lacazette and Aaron Ramsey scored two goals each as the Gunners hit four in 26 minutes before half-time.
Arsenal were unable to add to their tally in the second half but they will head to Russia's capital for the second leg next Thursday with a commanding lead.
"We have to be realistic. We have to do the job over there, go and try to win the game, that's the best way," said Wenger.
Ramsey's side-foot finish set Arsenal on their way.
Aleksandr Golovin levelled with a sublime free-kick before France striker Lacazette, who has recovered from a knee injury, made it 2-1 with a penalty after Mesut Ozil was fouled by Georgi Schennikov.
Ramsey produced a brilliant third with an instinctive volleyed flick, with Lacazette adding a fourth after being picked out by the outstanding Ozil.
"We have done half of a job," added Wenger. "There was a good pace in the first half, the two teams gave everything, which is why is was such a spectacular first half."
Gunners warming to Europa League
Arsenal, who have now won five straight games, should have triumphed by a more handsome margin in what was a cracking match.
Mkhitaryan missed a great chance early in the second half, while Ramsey fired over the bar after keeper Igor Akinfeev had spilled the ball into his path.
Ramsey's hopes of a hat-trick disappeared when his curling 77th-minute shot hit the post.
Nevertheless, Wenger's side will be confident of reaching the semi-finals of a competition that provides a team sixth in the Premier League - 13 points off fourth place with seven games left - with their most realistic chance of qualifying for next season's Champions League.
Arsenal are certainly warming to the Europa League, collecting their eighth win from 11 games in the competition, scoring 27 times and conceding eight.
Assuming there is no second-leg upset in Russia, they still need to negotiate a two-legged semi-final to reach the final in Lyon on 16 May.
Yet the way they dismantled CSKA, who started their European campaign in the Champions League, was impressive - although victory came at a cost.
Wenger confirmed after the game that keeper David Ospina, who suffered an ankle injury on the eve of the game, will be out for between two and three weeks, while Mkhitaryan, who was substituted, will miss Sunday's game against Southampton with a damaged knee.
Ramsey's special finish
There have been some spectacular goals in Europe this week.
Cristiano Ronaldo's superb overhead kick for Real Madrid against Juventus in the Champions League was followed by Alex Oxlade-Chamberlain's rocket shot for Liverpool against Manchester City.
Ramsey's second goal was also sumptuous.
The Gunners were leading 2-1 when the Wales midfielder, spotting Akinfeev off his line, lifted the ball over the CSKA keeper from Ozil's wonderful pass.
It was an audacious first-time finish and it left CSKA deflated as the Russian side conceded four goals in the space of 26 minutes.
"When Ramsey plays game after game he's not only involved in the build-up, he's now calmer in his finishing," added Wenger.
Ramsey had scored the first of Arsenal's four first-half goals with a finish high into the net and the midfielder, who scored against AC Milan in the last round at the San Siro, now has nine for the season.
He also had a goal ruled out for offside while the game was goalless before Arsenal went on to deliver a masterclass in attacking football.
Man of the match - Mesut Ozil (Arsenal)
Best first-half European goal blitz for 14 years - the stats
- This was the first time Arsenal scored four goals in the first half of a European game since December 2004 against Rosenberg in the Champions League group stage.
- The Gunners have won five matches in a row in all competitions for the first time since a run of six victories ending in May 2017.
- Arsene Wenger's side have won three consecutive knockout games in European competitions for the first time since 1999-2000, when they won four successive matches in the Uefa Cup quarter-finals and semi-finals.
- CSKA Moscow have now lost four successive European matches on English soil, shipping 10 goals in the process.
- Alexandre Lacazette has scored 10 goals in his last 13 Europa League appearances, these being his first two for Arsenal in the competition (after scoring eight for Lyon).
Arsenal are back at Emirates Stadium on Sunday when they host Southampton (14:15 BST), while CSKA Moscow host rivals Dynamo Moscow in a derby on Monday (17:30 BST), before next Thursday's second leg in the Russian capital.
- 24BellerínBooked at 78mins
- 29XhakaBooked at 57mins
- 10WilshereSubstituted forElnenyat 74'minutes
- 9LacazetteSubstituted forWelbeckat 74'minutes
- 77MkhitaryanSubstituted forIwobiat 61'minutes
- 35AkinfeevBooked at 74mins
- 66NatchoSubstituted forMilanovat 74'minutes
- 42SchennikovBooked at 58mins
- 10DzagoevBooked at 31minsSubstituted forCoelho Santosat 64'minutes
- 7MusaBooked at 51minsSubstituted forKhosonovat 83'minutes
- 11Coelho Santos
- Pavel Kralovec
- Shots on Target
Second Half ends, Arsenal 4, CSKA Moscow 1.
Offside, Arsenal. Nacho Monreal tries a through ball, but Mesut Özil is caught offside.
Foul by Granit Xhaka (Arsenal).
Aleksandr Golovin (CSKA Moscow) wins a free kick in the defensive half.
Alex Iwobi (Arsenal) wins a free kick in the defensive half.
Foul by Georgy Schennikov (CSKA Moscow).
Foul by Nacho Monreal (Arsenal).
Georgi Milanov (CSKA Moscow) wins a free kick in the defensive half.
Attempt missed. Pontus Wernbloom (CSKA Moscow) left footed shot from outside the box is close, but misses to the left. Assisted by Konstantin Kuchaev.
Attempt missed. Aaron Ramsey (Arsenal) left footed shot from the left side of the box misses to the right. Assisted by Alex Iwobi.
Attempt saved. Danny Welbeck (Arsenal) right footed shot from very close range is saved in the centre of the goal.
Substitution, CSKA Moscow. Khetag Khosonov replaces Ahmed Musa.
Mesut Özil (Arsenal) wins a free kick in the defensive half.
Foul by Georgy Schennikov (CSKA Moscow).
Attempt missed. Vitinho (CSKA Moscow) header from the centre of the box is just a bit too high. Assisted by Georgi Milanov with a cross following a set piece situation.
Héctor Bellerín (Arsenal) is shown the yellow card for a bad foul.
Foul by Héctor Bellerín (Arsenal).
Pontus Wernbloom (CSKA Moscow) wins a free kick on the left wing.
Aaron Ramsey (Arsenal) hits the right post with a right footed shot from the centre of the box. Assisted by Alex Iwobi.