The Czech Republic's Berdych finally put away the Spaniard 4-6, 6-4, 6-3, 1-6, 6-3 in three hours, 18 minutes to reach the last eight at Melbourne Park for a sixth straight year. 

Berdych has been a semi-finalist for the last two years in Melbourne and the Australian Open has proved the Czech's most successful Grand Slam based on match wins, now standing at 38-12.

It was Berdych's fourth win in six meetings with Bautista Agut, who upset former US Open champion and 12th seed Marin Cilic to reach the round of 16.

It was a battle for Berdych on Margaret Court Arena having his service broken four times, but he also broke the Spaniard's serve four times off a total of 22 break points.

The Czech hit a total of 66 winners, 28 of them off his signature forehand along with 18 aces, and dominated the battle at the net.

Berdych took his career five-set record to 18-8 as he gears for a possible tilt at Federer after losing to Andy Murray and Stan Wawrinka in semi-finals in the last two years.

"I always try to prepare the best I can and try to play well and the results are the proof and I am going to try to do the same for the rest of the tournament," Berdych said.

"I think this is my best base start to the year. It's a good one so far, I've got past the first week and now all the focus is on the second week."