Ashleigh Barty has continued her sizzling summer form by surging into the final four of the Sydney International.

A day after knocking off world No.1 Simona Halep, Barty broke the 12th-ranked Belgian Elise Mertens six times on her way to an emphatic 6-3 6-3 victory on Thursday on Ken Rosewall Arena.

“I’m pretty happy with the way I was able to come out here and play – nice and solid,” Barty said.

“I thought it was a little bit of a slow start but it was good to get the ball rolling mid to late in that first set.

“For us, it’s mostly about how I come out and play and try and lay my game, and not get too sucked in in how they play.”

Barty, the world No.15, will meet Yulia Putintseva or Kiki Bertens for a chance to avenge her defeat to Angelique Kerber in the 2018 final.

Kerber, who plays later on Thursday night and beat Barty last week in the Hopman Cup, remains alive on the other side of the draw.

The loss to the second-ranked Kerber is Barty’s only loss of the summer so far.

Earlier on Thursday, Aliaksandra Sasnovich’s impressive summer continued with a straight-sets win over Timea Bacsinszky.

The world No.33-ranked Sasnovich, who made it to the quarter-finals last week in Brisbane, was in control most of the way before prevailing 6-3 6-3 over her Swiss opponent.

The Belarusian, who knocked out Australian qualifier Priscilla Hon on Wednesday, will face Petra Kvitova or Kerber for a spot in the final.