Petr Cech was given a warm welcome to Arsenal by his new team-mates - although Theo Walcott could not resist a cheeky dig.
The 33-year-old on Monday completed his move from Chelsea, ending his 11-year stay at Stamford Bridge.
"Scored my first ever arsenal goal against him - delighted to welcome @PetrCech to @Arsenal !!! #WelcomeCech," Walcott wrote on Twitter, also posting a picture of the goal in question.
Gunners midfielder Aaron Ramsey hailed Arsene Wenger's latest recruit as one of the best goalkeepers the Premier League has had, tweeting: "Wow what a signing! One of the best @premierleague keepers ever! Welcome @PetrCech."
And Mesut Ozil said on Twitter: "From blue to red - welcome @PetrCech to the @Arsenal family! #YaGunnersYa #AFC #COYG #WelcomeCech."
Former Arsenal striker Ian Wright thanked Chelsea boss Jose Mourinho for allowing Cech to move to a rival Premier League club.
Speaking to BreatheSport, he said: 'I am absolutely delighted for Arsenal and, as a fan, I couldn't be happier. We finally have a world class stopper. Thank you Jose!"