Arsenal boss Arsene Wenger was at a loss to explain his side's appalling first-half display during its shock 2-1 loss to Watford at Emirates Stadium on Tuesday.

The Gunners managed just three wayward efforts on goal in the opening 45 minutes as they allowed the Hornets to canter to a two-goal lead and further damage its Premier League title hopes.

"It was not good in the first half, especially in the first 20 minutes. We were beaten in the duels and Watford were sharper than us," Wenger said.

"Did we think subconsciously that we just had to turn up? I don't know. Honestly, we prepared well for the game. Looking at the preparation, I have no basic regret.

"We knew that Watford would make it very physical and we prepared for that. You do not make 47 points after 23 games in the Premier League if you don't have physical power, but you have to switch it on 100 percent all of the time in the Premier League.

"We didn't start the way we wanted, but in the second half it was all us and let's be fair, we didn't deserve to lose this game.

"We hit the bar and (Watford goalkeeper Heurelho) Gomes made fantastic saves as well, so I still think that if you look at the chances, we were unlucky to lose.

"On top of that, we were a bit unlucky with the freekick for the first goal and then a deflected shot."

Younes Kaboul's deflected freekick gave Watford a 10th-minute lead, and the Hornets added a second three minutes later when Troy Deeney tucked in the rebound from an Etienne Capoue strike.

Bridge the gap

Arsenal, who replied through Alex Iwobi, takes on leader Chelsea at Stamford Bridge on Saturday.

Wenger said his team will not suffer from a hangover from this result. However, he was not comforted by Liverpool and Chelsea's draw or Tottenham's single point at Sunderland, which limited the ground Arsenal lost.

"We want to respond against Chelsea and win the game, of course," said Wenger.

"But we first have to analyze why we didn't start well in this game," added the Frenchman, whose team trails the Blues by nine points.

"I'm responsible for the results of the team so I am very frustrated that we did not win the game. We are playing at home, we had a great opportunity and we had a start like we did.

"We have to learn from that and respond very quickly and in a very convincing way. What the other teams do doesn't matter."

Wenger confirmed that Welsh midfielder Aaron Ramsey had limped off with a calf strain.

The result justified Watford boss Walter Mazzarri's decision to rest almost his entire first team for Sunday's 1-0 FA Cup loss to third-tier club Millwall.

The Italian made a point of dedicating the victory to former Hornets and England manager Graham Taylor, who passed away on Jan 12.

"My objective is for Watford to stay in the Premier League and to make my team grow game by game, week by week," said Mazzarri, whose team is 13th in the standings.

"Of course the players need this victory to work better with me and also to believe that they can achieve great things.

"I was very happy at the end because recently we deserved to win some games, but didn't because luck was not on our side. We needed a big win, especially for the morale of the team.

"Of course I would have liked us to play the whole 90 minutes like we did in the first half.

"But we had at least four or five players coming back from injury and who hadn't played 90 minutes for a long time, so they weren't in condition to play the full 90 minutes at the same level.

"Today was a great game and I want to dedicate this victory to a great person in Graham Taylor."