New Sunderland defender Papy Djilobodji wants to demonstrate that he was good enough to play for Chelsea.
Djilobodji, 27, last week became David Moyes' first purchase as Sunderland manager for a reported fee of £8 million.
A surprise signing for Chelsea last September, the Senegalese centre-back spent the second half of last season on loan at Werder Bremen.
Djilobodji's goal on the final day of Bremen's Bundesliga campaign saved the German club from relegation but he then felt the need to prove himself in the Premier League. "At the end of the season, they wanted me to stay but I was on loan and I wanted to return to England," Djilobodji told L'Equipe.