He made his debut five days later on 27 August 2006, in the starting eleven in a 0–0 draw against Heracles Almelo. In his second appearance against Sparta Rotterdam on 10 September 2016, he suffered a hamstring injury and was substituted in the 68th minute, as the club won 4–1. However, he recovered quickly and made his European debut as a starter in the first round of the UEFA Cup, a 2–2 draw against Lokomotiv Sofia. The club reached the Group Stage after drawing 0–0, going through on away goals. In a match against Willem II on 12 November 2006, he was sent off after handling the ball on the goal-line in the 78th minute, as Feyenoord won 5–3. Following the match, however, video evidence showed that Tiendalli had not committed an offence; referee Jack van Hulten admitted his mistake and the red card was rescinded. He became a first-team regular for Feyenoord in the first half of the season, but was later sidelined with injuries, including a groin injury meaning he was expected to miss the entire season. By March, he was sufficiently recovered to resume training, and returned to the starting line-up on 22 April 2007 in a 1–1 draw with NEC Nijmegen. In his first season at Feyenoord, Tiendalli made nineteen appearances in all competitions.