By SABC Sport
5th August 2023
The 36-year-old, who was runner-up in Washington 17 years ago, looked on the brink of another of his occasional statement wins since his comeback from hip surgery when he had break points for a 4-2 lead in the deciding set.
But Fritz, the top seed and American number one, managed to repel all three and went on to wrap up his 40th win in 2023, 6-7 (2) 6-3 6-4.
An epic encounter was briefly held up while a group of rowdy protesters who had thrown giant tennis balls on to the court were escorted from the stand.
Murray had already smashed his racket against the floor after dropping serve in the first game, throwing in two double-faults among six unforced errors.
The Scot had been a point away from a 3-0 deficit but improved as the set wore on and broke back for 5-5 as Fritz served for it, saving two set points before converting his first break point with a drop shot.
Murray dominated the tie-break with Fritz now showing his frustration, and he took the set after 87 minutes with an almost dismissive forehand winner.
But Fritz locked straight back in to break at the start of the second on his way to levelling the match.
Fritz survived those break points at 2-3 in the decider and then a Murray double-fault gifted the 25-year-old three chances to break, taking the second when Murray's backhand drifted long.
In a dramatic final game, Murray brought up three break-back points at 0-40 but Fritz survived the lot and then squandered two match points before converting the third.
Dan Evans had lost eight of his last nine matches before arriving in Washington but the British number two made it two wins in two by beating Russia's Alexander Shevchenko 6-4 6-3.
He doubled down on his impressive performance with a 6-4 7-5 win over Frances Tiafoe later in the day after rain saw his and Murray's matches cancelled on Thursday.
Evans broke the American second seed in the opening game of both sets and was able to overcome 16 aces from Tiafoe with some superb attacking tennis, particularly down the stretch.
He is set to face fifth seed Grigor Dimitrov in the semi-finals.