Arsene Wenger labelled Alexis Sanchez world class and warned he is back to his best after his Arsenal treble gunned down Leicester.
The forward scored a classy hat-trick as the Gunners ended Leicester's unbeaten start to the Barclays Premier League season.
Theo Walcott and Olivier Giroud also netted to clinch a 5-2 win and Arsenal are now just three points behind new leaders Manchester United - who they host next Sunday.
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They had to come from behind at the King Power Stadium after Jamie Vardy's opener but Wenger believes Sanchez, who scored his first Arsenal goals since last season's FA Cup final, showed why he is world class.
He said: "I think he is. I think I have plenty of players who are world class but you always have to understand what the definition of that is.
"Overall he is a striker who is mobile and works hard for the team and when the team plays well he can score goals.
"He is back to his level. He won a big competition with Chile - the Copa America - and to adjust again to a competitive level when you come back takes some time."
"We could see in training already a different player in the last week or two.
"He showed that in this game and overall I thought we always looked dangerous going forwards."
Beaten Leicester boss Claudio Ranieri added: "It's fantastic, I've known him (Sanchez) since he played in Italy, when he plays at this level he is an amazing player and can do everything. The ball and him are both together."
Manchester City's 4-1 defeat at Tottenham earlier in the day allowed Arsenal to close the gap at the top and Wenger admitted the title race is wide open.
"Of course. Knowing that Tottenham had beaten Manchester City made the whole league very tight," he said.
"Two weeks ago we had Manchester City playing West Ham at home so you would expect them to make the difference."
Vardy scored a late consolation and also hit the woodwork twice in the first half and has now scored six goals this season, one more than he did last year.
And Ranieri refused to be downbeat following the Foxes' first defeat of the season.
He said: "I think we are sad because we wanted to continue to be unbeaten. It's important to learn something but now the reaction is important in the next match.
"They showed the maximum character. I understand it's difficult to play a team who use one or two touches. It's impossible, when you go to press they move the ball very quickly.
"The quality of the Arsenal players is a very high level. We tried to do our best and created good chances, some were unlucky, (Petr) Cech made a good save and it's important how we react in the next match."