Arsenal manager Arsene Wenger believes his side are proving themselves a "different team" as the Premier League season run-in approaches after seeing off the challenge of West Ham 3-0 at the Emirates Stadium.
The Gunners recorded an eighth home league victory to keep the pressure up on second-placed Manchester City after finally ending what was a spirited second-half effort from the Irons.
Theo Walcott, recalled to the starting XI following injury to Alex Oxlade-Chamberlain, had missed a couple of early chances before goalkeeper Adrian was beaten on the stroke of half-time by a fierce angled drive by Olivier Giroud, which cannoned in off the far post.
West Ham, who have plummeted down the table following a poor run of results, regrouped for the second half and would have been good value for an equaliser.
However, Arsenal finally broke them down again with nine minutes left when Aaron Ramsey fired in after a neat one-two with Giroud and substitute Mathieu Flamini rolled home a third to send Wenger's side into next week's Champions League tie away to Monaco with renewed hope of an unlikely victory.
"We just have to keep going. We have won eight of the last nine and we are stronger today than we were at the start of the season," said Wenger.
"We dropped off in this league because we won one of six at the start of the season. Today we are a different team.
"We suffered a lot from the post-World Cup fixtures, players came back and they weren't ready to play."
Giroud's goal finished off a classic slick Arsenal passing move as the France forward continued his fine recent form, with six goals in the last seven.
"It was a fantastic goal because it's a consequence of a fantastic combination just before and after. On top of that the finishing was great," said Wenger.
"Giroud is a boy who has played at 22 or 23 in division three [in France]. He's come out and has become an international footballer.
"You need some mental strength to do that because there's no red carpet there. You have to work hard to get out there and get to the top -- you need some special strength."
Wenger takes Arsenal to his former club on Tuesday night needing to overcome a 3-1 deficit from the first leg, something which has never been done in the Champions League before.
He said: "We have come out of a good week because we have played at Manchester United [in the FA Cup], we have played the London derby today and we need the belief to prepare well for Monaco. Let's do that and after we will see.
"If you have no belief you have no chance. We have to believe that we can do it.
"This time Monaco are favourites so we have to go there, give absolutely everything."