Andy Murray continued his eventful start to the season with a notable win over Germany's Alexander Zverev to put him into the Qatar Open quarter-finals.
Britain's Murray, 35, dug deep into his physical and mental reserves yet again to win 7-6 (7-5) 2-6 7-5 after an absorbing three-hour match in Doha.
"I managed to stay strong, keep fighting and get the break at the end," said the former world number one.
French qualifier Alexandre Muller, ranked 170th, awaits Murray next.
"I would like to win the matches quicker but Alex is a top player and a great competitor, who always fights until the end," added Scot Murray after upsetting fourth seed Zverev.