Chennai, India (SportsNetwork.com) - Seventh seed Marcel Granollers went by way of an upset Monday at the season-opening Chennai Open.

Austrian Andreas Haider-Maurer knocked out the Spaniard Granollers 3-6, 7-6 (8-6), 2-0, retired on the hardcourts at SDAT Tennis Stadium. Granollers succumbed to a knee injury on Day 1.

Also, eighth-seeded Gilles Muller of Luxembourg rifled 29 aces in outlasting Frenchman and 2014 Chennai runner-up Edouard Roger-Vasselin 6-7 (11-13), 6-1, 7-6 (7-3) in 2 hours, 24 minutes and rising young Croat Borna Coric leveled Dutchman Robin Haase 6-2, 6-2 at this Australian Open tune-up.

This week's top seed is Aussie Open champ and reigning Chennai titlist Stan Wawrinka, who will open his 2015 campaign against the 18-year-old Coric.

The two-time Chennai champion Wawrinka beat Roger-Vasselin in last year's finale here.