Two-time champion Marin Cilic of Croatia has entered the quarterfinals of the Aircel Chennai Open ATP tennis tournament. He came from behind to beat Sergiy Stakhovsky of Ukraine 4-6, 6-2, 6-2. It took Cilic 110 minutes to see off the challenge of Stakhovsky. In a doubles match, at the outside court, German pair of Andre Begemann and Martin Emmrich survived some anxious moments before prevailing over the English duo of Jamie Delgao and Ken Skupski 7-6, 6-1 in 64 minutes.They will meet the winner of the match between Somdev Devvarman/Stakhovsky and Thailand's Sonchat and Sanchai Ratiwatana.