After his loan spell ended, Tiendalli was told by Feyenoord that he could leave the club despite his being keen to stay and take his chance. Tiendalli ended up staying at Feyenoord over the summer, because of the club’s asking price. At the start of the 2008–09 season, he found himself playing for the reserve side. A month later, on 26 October 2008, Tiendalli made his first senior appearance of the season, in a 2–2 draw with SC Heerenveen. Following his return to the first team, he was involved more often by the club, until he was sent off for a second bookable offence in a 2–0 defeat in De Klassieker, Feyenoord's highly contested match with Ajax, on 15 February 2009. Following his return, Tiendalli failed to make his hoped-for breakthrough into regular first-team contention. He was sent off again in the last game of the season, a 3–2 defeat to Roda JC, for a professional foul in the 19th minute. Despite injuries and suspensions, he made twenty-eight appearances in all competitions during the 2008–09 season.