Grigor Dimitrov gave his chances of qualifying for next month's ATP World Tour Finals another significant boost with a straight sets victory over Mischa Zverev at the Stockholm Open.
Dimitrov defeated 5th seed Zverev 6-3, 6-4 to move a step closer to his second Stockholm Open title, having been crowned as champion of the tournament in 2013.
The Bulgarian -- seeded first in Sweden -- is now just two wins away from securing his fourth ATP Tour title of the year as he looks to add to the crowns he picked up in Cincinnati, Sofia and Brisbane.
His triumph sees him book a meeting with Italian Fabio Fognini after the Italian battled from a set down to defeat America's Jack Sock in the opening match of the day.
Despite falling 6-7 (3) in the first set, Fognini recovered to take the remaining sets 7-6 (2), 7-5 and edge past the No. 3 seed in a gruelling contest which fell just short of three hour mark.
In the other half of the draw, last year's winner Juan Martin del Potro helped his chances of defending his crown as he saw off Japan's Yuichi Sugita 6-2, 7-6 (6) to move into the semifinals.
Del Potro -- who returned to the Top 20 of the ATP Rankings for the first time since 2014 at the start of the week -- will play former World No. 7 Fernando Verdasco for a place in Sunday's final.
The Spaniard stunned No. 2 seed Kevin Anderson 7-6 (1), 7-6 (1) to set up a match with the Argentinian.