Barcelona: Defending champion Kei Nishikori thrashed Colombian 15th seed Santiago Giraldo 6-2, 6-1 to move into the quarter-finals of the Barcelona Open on Thursday.

The Japanese top seed is making his first appearance of the season on clay in the Catalan capital, but showed no signs of rustiness early on as he romped into a 4-0 lead.

Giraldo responded by getting a break of serve back at 4-2, but Nishikori then reeled off the next seven games to take him to the brink of victory and he served it out to make the last eight with ease.

The world number five will face either Spain’s Roberto Bautista Agut or Uruguayan Pablo Cuevas on Friday.

Rafael Nadal is scheduled to take on Italian Fabio Fognini later.

Meanwhile, in Stuttgart, Romanian Simona Halep overcame Spanish Garbine Muguruza in three tough sets to become the first player to enter the quarter-finals of the Porsche Tennis Grand Prix.

World No. 20 Muguruza took the first set of this one in just 34 minutes, 6-3, coming through on the big points much better than Halep.

But the No.2-seeded Halep fought back, claiming the second set, 6-1, and battling back from 0-2 down in the third set to win the match, 3-6, 6-1, 6-3.