 Complete the following phrase:  Once he arrived in Rotterdam Collen started on the bench. Due to good play in training, he forced himself into the squad and played many good matches in the Dutch top flight as well as in the UEFA Champions League. However, a string of injuries and a long period of rehabilitation caused him to be sidelined until the end of the 2002 season. He was part of the Feyenoord squad that won the 200102 UEFA Cup, as an unused substitute in the 