London - Arsenal manager Arsene Wenger was at a loss to explain his side's appalling first-half display during their surprise 2-1 defeat by Watford at the Emirates Stadium.
His side mustered just three wayward efforts on goal in the opening 45 minutes as they allowed Watford to canter into a two-goal lead and damage further their tilt at the Premier League title.
"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 admitted after Tuesday's match.
"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 free-kick for the first goal and then a deflected shot on top of that."
Younes Kaboul's deflected free-kick gave Watford a 10th-minute lead and Watford added a second three minutes later when Troy Deeney tucked in the rebound from Etienne Capoue's shot.
Arsenal, who replied through Alex Iwobi, travel to leaders Chelsea on Saturday and Wenger insisted his team will not suffer from a hangover from this result.
Nor was he comforted by draws for Chelsea, Liverpool and Tottenham Hotspur, which limited the ground Arsenal lost.
"We want to respond against Chelsea and win the game, of course. But we first have to analyse why we didn't start well in this game," said the Frenchman, whose team now trail Chelsea 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.
For Watford manager Walter Mazzari, the result justified his decision to rest almost his entire first team for Sunday's FA Cup defeat by third-tier Millwall.
The Italian made a point of dedicating the victory to former Watford manager Graham Taylor, who passed away on January 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 side sit 13th.
"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."