The quiet 21-year-old has been the breakout star for Australian tennis this year, with her victory over Martina Trevisan in the first round being another landmark moment in a season in which she's rocketed from No.118 in the world to 62.
But tackling Russia's world No.20 Diana Shnaider in the last-64 on Friday proved a hurdle too far for the Perth prospect, who's still a clay-court novice, as she succumbed 5-7 6-1 6-1 to end the Australian women's interest in the WTA 1000 singles event at the Foro Italico.
Gibson had looked as if she might be in the mood to make another leap forward as she came from behind in a really tight opening set, reeling off three-straight games for the loss of just three points to take it 7-5 after just under an hour.
As a wildcard, she had faced Shnaider at the Australian Open and held three match points against her, only to lose out 6-3 in the third, so must have fancied her chances of going one better this time.
But that first-set annexation proved as good as it would get, as the Russian powered through the next four games to take a grip she wouldn't release against the west Australian, who made such spectacular progress when defeating five top-20 players in Indian Wells and Miami.
Iga Swiatek was one of several players struck down by illness in Madrid, but now it's her coach, Francisco Roig, who's ailing - thanks to a bet that went wrong.
Spaniard Roig, who linked up with Swiatek last month following his split from Emma Raducanu, needed surgery after tearing his Achilles during a practice game with the Pole.
"Yeah, I broke my coach's Achilles," fourth-seed Swiatek joked after beating Caty McNally 6-1 6-7 (5-7) 6-3.
"Basically we're having a practice on Piazza del Popolo on Saturday. It was supposed to be a live practice ... We made a bet for 100 euros.
"I had 5-4 and the match point already. He did a split step and tore his Achilles. On Tuesday, he had surgery already in Warsaw. We kind of took care of him. He basically just missed one practice.
"For sure it's not easy right now in the practices because he can't be next to me but we'll make it work."
There were also second-round victories for Elena Rybakina, Naomi Osaka, Jessica Pegula and Madison Keys.