London - Arsenal midfielder Mathieu Flamini has stoked the fires ahead of the Gunners' Community Shield meeting with Chelsea on Sunday by saying the champions have done them a "good favour" by selling Petr Cech.
The Czech goalkeeper ended an 11-year stint at Stamford Bridge after moving across London to the Emirates Stadium last month for a fee of £10.9 million.
"I was surprised by (Chelsea boss Jose) Mourinho because he really doesn't do that," Flamini told British media on Thursday.
"He (Mourinho) is a competitor and usually doesn't like to sell any players to his rivals, but it's a good favour for us and now we have to take advantage.
"It's a top signing. That's why we have been lucky on this one," added the French midfielder.
The 33-year-old Cech was allowed to move from west to north London, despite Mourinho's reluctance to let him go, after losing his place in the Chelsea side to Belgian international Thibaut Courtois.
And Cech, who made nearly 500 appearances for Chelsea, will face the surreal task of playing against them for the first time in his career when his new club meets his old one on Sunday at Wembley.
Arsenal, who finished third in the Premier League last season, 12 points behind champions Chelsea, face an early test of their title credentials for the upcoming season, but 31-year-old Flamini believes the acquisition of Cech could prove crucial.
"It's very important. Not only for his quality but also for his character," added Flamini.
"When you play at the top level, the leaders on the pitch make the difference.
"Not only when things go well but especially when things go bad. So, for us, Petr Cech is a top signing.
"He is someone with character, someone with a winning mentality."
Cech is Arsenal's only major signing so far this summer, but having spent big money on the likes of Danny Welbeck, Mesut Ozil and Alexis Sanchez in recent seasons, Arsene Wenger's side - who won the FA Cup last season for the second consecutive campaign - are once again considered as potential challengers for the Premier League title.
Arsenal downed Manchester City 3-0 in last season's Community Shield.