Rio de Janeiro, Feb 23 (IANS): Slovenia's Aljaz Bedene continued his strong run of form in the South American clay-court season, defeating Spain's Pablo Carreño Busta 6-2, 5-7, 6-2 to advance to the quarter-finals of the Rio Open.

One week after reaching the final of the Argentina Open, the 43rd-ranked Bedene on Thursday used his strong return game to upset the Spanish World No.11, a 2017 US Open semi-finalist, reports Efe.

Carreño Busta, runner-up in last year's event, was far off his regular form in the first set and appeared to be struggling physically even though he did not take a medical time-out for muscle pain that had forced him to withdraw from the Rio Open doubles.

The second set began in similar fashion, with the Spaniard dropping his opening service game.

A power outage then forced tournament organisers to suspend the match for nearly a half hour, an interruption that worked in the favour of Carreño Busta, who immediately got the break back and then grabbed a 2-1 lead.

The Spaniard went on to break his opponent's serve two more times en route to taking the first set.

But his inability to control his own service games proved his undoing in the third set, when he won just one of eight second-serve points and was broken on three occasions.

Next up for Bedene in Friday's quarter-finals will be fifth-seeded Italian Fabio Fognini, who edged out American Tennys Sandgren 4-6, 6-4, 7-6(8-6) on Thursday.

In other second-round action on Thursday, Frenchman Gael Monfils upset top-seeded and third-ranked Croatian Marin Cilic 6-3, 7-6 (10-8) in a match that began the day before but was postponed by rain.