The wildcard duo, who'd never played together before their unexpected triumph at Melbourne Park in January, were hardly able to credit how they knocked out three top-10 seeds and went on to succeed Nick Kyrgios and Thanasi Kokkinakis as Australian Open champions.
Installed as 15th seeds and seen as genuine contenders in Paris, they had been hopeful of causing more upsets only to go down fighting 7-6 (7-4) 7-6 (7-5) to Portugal's Francisco Cabral and Brazilian Rafael Matos in the first round on Tuesday morning.
With each pair grabbing a break apiece in the two-hour contest, the match came down to two tight breakers, with the Australian pair having to cling on in the second-set denouement, saving two match points at 5-6 down.
In the tiebreak that followed, they still kept themselves alive, fighting back from 5-2 down to level at 5-5, but it wasn't enough.
It means the end of the chances of another grand slam-winning Aussie men's team, this time at Roland Garros, following Hijikata and Kubler's victory in Melbourne and Max Purcell and Matt Ebden triumphing at Wimbledon.
Kokkinakis, who had teamed up with Jan-Lennard Struff before hoping to reunite with Kyrgios at Wimbledon, also got knocked out with his new German partner on Tuesday, losing 7-6 (7-1) 3-6 6-3 to Italians Fabio Fognini and Simone Bolelli.
Purcell, though, plans to play his first round match with young American gun Brian Shelton on Wednesday against Britons Julian Cash and Henry Patten, despite the ankle injury that troubled him in his singles win over Jordan Thompson.
