Jannik Sinner and other top seeds move through to Round of 16 at Miami Open

Sinner would emerge the victor after a tense 5-7 7-5 6-1 tussle against Griekspoor to book his place in the Round of 16.

Hungary's Fabian Marozsan caused a major upset as he knocked out world number seven Holger Rune 6-1 6-1.

"It is a great feeling to play at the highest level," Marozsan said.

"I try to play my best tennis and today against a top 10 player and I am enjoying my time here. I try to play my best tennis."

British number one Cameron Norrie bowed out as he was beaten 7-5 6-1 by number three seed Daniil Medvedev in a little over 80 minutes.

Two early breaks left Norrie with too much to do in the opening set and Medvedev asserted his control to run away with the second set.

Medvedev will face Germany's Dominik Koepfer, who came from behind to beat French 14th seed Ugo Humbert 3-6 6-4 6-3.

Seventh seed Casper Ruud saw off Alejandro Davidovich Fokina 6-3 6-4 to book a clash with Nicolas Jarry, who beat Thiago Seyboth Wild 6-7 7-5 6-3.

Finally, Andy Murray raged at umpire Carlos Bernardes as he was knocked out following a dramatic three-set defeat to Tomas Machac.

Murray appeared to be furious with Bernardes for failing to control the movement of spectators around the Butch Buchholz court as he lost his serve at the end of the second set.

Machac then raced into a 3-0 lead in the decider and eventually closed out a 5-7 7-5 7-6 (7/5) victory in three hours and 27 minutes, but only after Murray had survived an injury scare and saved a match point to force the tie-break.

Murray had taken the first set after finally capitalising on his ninth break point and, following a 40-minute rain delay, the second set looked destined for a tie-break until Murray lost his serve in the 12th game.

The 36-year-old's frustrations with fans moving between points boiled over and he could be heard shouting to Bernardes: "Useless, useless."

In response to an unheard reply from Bernardes, Murray responded: "What are you talking about? It's quite obvious when people are standing up between every single point."

It was no surprise that a distracted Murray then lost his serve at the start of the decider but Machac was unable to close out the match at 5-3, serving two double faults as he let Murray back into the contest.

Murray looked to have all the momentum but then seemed to twist his ankle as he ran towards the net after levelling at 5-5, the former world number one thankfully able to continue after being assessed by a tournament physio.

In typical fashion, Murray refused to throw in the towel and saved a match point on his own serve to take the contest to a decisive tie-break which he led 5-3, only for Machac to reel off four points in a row to complete a remarkable win.