Giant-killing Jakub Mensik's Australian Open ended Friday at the hands of Spain's Alejandro Davidovich Fokina as the 19-year-old Czech crashed out in five gruelling sets.

Mensik stunned sixth seed Casper Ruud en route to the third round and looked on track for another win when he took a two-set lead in Melbourne.

He had a match point in the third-set tie break but failed to convert and the more experienced Davidovich Fokina ground his way back as Mensik ran out of puff.

The 66th-ranked Spaniard eventually got over the line 3-6, 4-6, 7-6 (9/7), 6-4, 6-2 after a draining 3hrs 30mins.

It set him up with a clash against 12th seed Tommy Paul for a place in the quarter-finals after the American downed another Spaniard, Roberto Carballes Baena, in straight sets.

"Wow, I don't know how to describe my feelings," said Davidovich Fokina, who made the fourth round for the first time.

"Three wins for the first time in Australia, it means a lot."

Mensik is one of a trio of teens who set the Australian Open alight with wins over top-10 players, alongside Brazil's Joao Fonseca and American Learner Tien.

While Mensik and the highly rated Fonseca are now out, Tien is still alive after a massive five-set upset of fifth seed Daniil Medvedev.

He plays his third-round match against Frenchman Corentin Moutet on Saturday.

mp/pst