On her 33rd birthday, former No.1 Ajla Tomljanovic ran into another of the Italian youngsters who are following the Jannik Sinner and Jasmine Paolini trail as she was defeated by qualifier Noemi Basiletti 7-5 6-4 on Thursday.
Then Maya Joint, the current leader of the pack, returned to the court after a two-month injury break, only to deliver a rusty, error-strewn performance in a 7-5 6-2 defeat to Swiss Viktorija Golubic.
That leaves 21-year-old Gibson the sole Aussie woman left in the last-64 as she prepares to tackle Russian 19th seed Diana Shnaider in the second round on Friday.
Tomljanovic had to resume her opening match on Thursday, which had been held over because of the rain in Rome, with her 20-year-old opponent holding on to an overnight 5-3 first-set lead.
Australia's birthday girl Tomljanovic, who'd been knocked out in the qualifiers, probably felt her real present was still being in the competition after she'd been handed a 'lucky loser' spot when Marta Kostyuk pulled out with hip and ankle problems.
But world No. 427 Basiletti, a wildcard playing the first WTA main-draw match of her career after a spectacular run through qualifiers where she beat two other top-100 players, was determined to make Tomljanovic her third high-profile victim and took the opening set even after the Australian had levelled at 5-5.
In the second set, world No.88 Tomljanovic appeared as if she might be gradually wearing her much-lower ranked and inexperienced opponent down as she hit back from 4-1 down to level, but she then coughed up a poor service game at 4-5, eventually succumbing on the third match point after two hours.
World No.34 Joint, who's been out with a back injury, unsurprisingly looked out of sorts to start with in her comeback outing, the 20-year-old swiftly going 4-0 down before beginning to find her range just a bit too late in the opening stanza.
The US-born Queenslander did produce some encouraging shotmaking, but it was mixed with far too many unforced errors - 18 in each set - although there was nothing wrong with her fighting spirit as she saved six match points in the penultimate game before succumbing to veteran world No.90 Golubic.
The tournament's big guns started firing on Thursday with world no.1 Aryna Sabalenka easing past former Wimbledon and French Open champ Barbora Krecjikova 6-2 6-3, Coco Gauff defeating Czech Tereza Valentova 6-3 6-4 and Paolini beating Frenchwoman Leolia Jeanjean 6-7 (4-7) 6-2 6-4.
