Nishikori defeats Sousa to reach last 16 in Australian Open
The number 8 seed overcame a tight start and routed his opponent 7-6(6) 6-1 6-2 in two hours and six minutes, EFE reports.
"I love to play on this court. I feel very comfortable, and it's been three in a row playing here," said Nishikori after the match.
"Everything is doing well - I had a very good off-season, then winning Brisbane, it's been a good start to the year. I finished in three good sets today, I'm playing good tennis, and very much looking forward to next week," he added.
Nishikori coughed up a break in the opening game, but recovered to level up at 2-2.
Sousa saved a virtual set point to hold for 5-6 before Nishikori sent the opener into a tiebreak.
The former U.S. Open finalist will now play against Fabio Fognini or Pablo Carreno Busta in the last 16.