(CNN)Three-time grand slam champion Andy Murray says he "lost respect" for Stefanos Tsitsipas, after the Greek world No. 3 took multiple extended breaks at crucial times during their first round US Open match.

The pair battled it out for more than four-and-a-half hours in a five-set thriller, with Tsitsipas eventually prevailing 2-6 7-6 3-6 6-3 6-4 to advance to the second round at Flushing Meadows.