Twice former champion Kei Nishikori sealed his place in the quarter-finals of the Barcelona Open with a straight sets win over Felix Auger-Aliassime on Thursday. The fourth seed broke his Canadian opponent's serve three times in four games on the way to taking the opening set 6-1. Nishikori then broke for a 3-1 lead in the second set, but although Auger-Aliassime was unable to convert any of his five break points in the next game, the 16th seed broke to love in the seventh to trail 4-3. The 18-year-old failed to hold serve in the following game though and Nishikori moved ahead 5-3 before serving out a 6-1, 6-3 victory. Japan's Nishikori, who won the tournament in 2014 and 2015 before losing to Rafael Nadal in the 2016 final, will face either Roberto Carballes Baena or Christian Garin in the last eight.