Stan Wawrinka and Gael Monfils have withdrawn from the Cologne 2 event this week.
No.18 ranked Wawrinka kicked off his indoor season at the St. Petersburg Open this week eventually losing to Canadian Denis Shapovalov in straight sets.
Former world No. 6 Monfils says he isn’t ready to return to action and will take another week off before making his return.
He last played at the French Open, losing in the round loss to Kazakhstan’s Alexander Bublik.