Mikel Arteta was delighted with Arsenal's clinical victory over Slavia Prague but has warned his side face a tough test against former boss Unai Emery's Villarreal in the Europa League semi-finals.

The Gunners entered Thursday's quarter-final second leg with the tie delicately poised at 1-1, but they produced one of their best displays under Arteta to win 4-0 at Sinobo Stadium and advance 5-1 on aggregate.

Nicolas Pepe added to his first-leg strike by opening the scoring in the Czech capital, setting Arsenal on their way to a straightforward win as an Alexandre Lacazette penalty and long-range Bukayo Saka strike followed inside the first 24 minutes.

Lacazette rounded off the scoring in the second half to confirm a semi-final tie with Villarreal - 3-1 aggregate winners over Dinamo Zagreb - and a reunion with Emery, who was sacked by Arsenal in November 2019 and replaced by Arteta.

Emery has previously won the Europa League three times with Sevilla, while also losing the 2018-19 final against Chelsea during his time at Arsenal, and Arteta is aware of the size of the task now facing his side over two legs.

"It will be really tough and Unai Emery is probably the most successful manager in this competition," he told BT Sport. "There is still a lot to do and things we can improve on, but we have a real desire to improve and be better every day."

Arsenal are effectively relying on the Europa League to salvage their campaign and secure a place in Europe next season, the Gunners sitting ninth in the Premier League with seven games to play.

Arteta was particularly pleased with the way his side responded to having an Emile Smith Rowe goal chalked off at 0-0 on the day as his side held on for back-to-back clean sheets, and a first shutout in eight European games

"We started really well in a convincing way, aggressive in our high press," he said. "We looked a threat all the time. 

"I really like the reaction of the team to the goal being disallowed. We scored some great goals. The clean sheet is important as well, the second one in two games.

"It helped the way we played against Sheffield United. The players were in high confidence, when performances are so high the collective improves. The boys were really at it from the start.

"It is a really important win in a crucial moment. We won in a convincing way, so credit to the players."

Smith Rowe may have been denied a goal by VAR, but he set up Pepe for the opener - his seventh assist in all competitions this season, which is the joint-most of any Arsenal player alongside Willian.

With his strike later in the first half, meanwhile, Saka became Arsenal's joint-top teenage scorer in major European competition, matching the four goals scored by Charlie George and Ray Kennedy.

"For me it's a joy to watch them play to watch them every day in training," Arteta said at his post-match news conference when asked about the young pair's performance. "The passion and the commitment they have for the club is special.

"I'm really happy with all of the players. We came to a tough place to face a team that hasn't lost at home in almost two years.

"I think when we demanded efficiency from them and today is a good example of the efficiency you need in Europe to win matches."

Saka, who now has seven goals to his name in all competitions this season, added to BT Sport: "It shows everyone how exciting we can be. When we play like this it is so amazing to be involved in. 

"We have a chance of going to the final and winning this competition - now it is up to us. We look forward to the next opponent."