The Swiss, on his first outing since a third-round loss to Milos Raonic at the US Open, advanced 7-5 7-6 (7-5) in a hard-fought encounter.

Wawrinka, a three-time major champion, has dropped to 88th in the world due to injury woe and found himself a break down midway through the opening set.

But a fine forehand winner set up two break-back points in game 10 and he converted the second as Bedene went long before the Swiss harnessed the momentum as another passing shot on the forehand side secured him the set.

Wawrinka rescued four break points in the second to force a tie-break where, at 5-5, Bedene made a pair of forehand errors to send his opponent through to a clash with fourth seed Khachanov, who was given a first-round bye.

"I'm really happy to be back," said Wawrinka, a runner-up at the tournament two years ago. "I'm happy to play again here, it's a great tournament. I love the city and I'm happy with the first win.

"[Khachanov] is a very good player, he's improved a lot. He's young, it'll be a tough match for sure, he's a strong player playing hard from the baseline, I expect a tough match.