Indian Wells: Australian Open champ Switzerland’s Stanislas Wawrinka is not confident of winning another Grand Slam.

Stanislas Wawrinka

“I’m not sure if I can win a Grand Slam again. For sure it's going to be really, really difficult. I know I did it already. I know that I can reach that level, but it's going to be tough,” Wawrinka said after he teamed with Roger Federer to beat Rohan Bopanna and Aisam-Ul-Haq Qureshi 6-2, 6-7 (4/7) 10-6 in Round 1.