London - William Gallas insisted on Monday he had not moved from Arsenal to north London rivals Tottenham Hotspur lightly but the France defender promised to give his new club "everything".
The 33-year-old Gallas is not the first player to move from one of the bitter rivals to the other and there are signs supporters of both clubs are far from happy at the move.
"It was not an easy decision but I am here now and I will give my best," Gallas told his new club's official website, www.tottenhamhotspur.com.
"What is most important to me is to play games and to give everything."
Gallas added he'd joined a club capable of winning the English Premier League this season.
"Finishing fourth last season shows Spurs have improved a lot and I hope this season we are going to finish even higher, maybe even win the Premier League," he added.
"We just have to believe in ourselves. We have got young players with great quality.
"They just have to believe in their capacity to do something and I hope we can achieve this." Tottenham manager Harry Redknapp revealed on Friday he had been in talks with two-time Premier League winner Gallas for several weeks and his new signing said: "The atmosphere is great.
"I like that and I'm just looking forward to playing as soon as possible and winning some games."
Gallas, at least two weeks away from being match ready, added: "I just want to be fit as soon as possible, train with my team-mates and play matches. I want to show everybody I am still here." He will miss Wednesday's must-win Champions League clash with Young Boys but will feature if Tottenham overturn a 3-2 play-off round deficit and go through to the group stage.
"Spurs are ready for the Champions League, even though they lost the first game," said Gallas, who has played in Europe's premier club competition for the past seven seasons.
"I have seen the game and the team showed character to come back (from 3-0 down).
"I am confident we will win that game on Wednesday because all the players know it is very important to play in the Champions League.
"I have played many games in the Champions League. It is the best level to play at as you are up against the biggest teams and you can show how good you are.
"The atmosphere is so great. When you hear the music, you just want to get on the pitch and battle for 90 minutes, and it would be good for Spurs." Tottenham are still waiting on the fitness of several key players.
England striker Jermain Defoe (groin) could return but Luka Modric (groin), Roman Pavyluchenko (ankle), Giovani dos Santos (hamstring) and Robbie Keane (knee) all remain doubtful.