The 70-minute encounter at the AXA Training Centre ended goalless, with the Reds fielding a strong side featuring Alexis Mac Allister, Federico Chiesa and Kostas Tsimikas.
Dossena sustained the injury after landing awkwardly on his hand while challenging for an aerial ball involving James McConnell and Will Wright.
The Como defender’s severely dislocated finger was shown in a close-up television shot, prompting LFCTV commentators to apologise to viewers.
Despite the alarming injury, the 27-year-old showed impressive determination.
After receiving treatment and having his finger bandaged by Como’s medical staff, Dossena returned to the pitch.
Remarkably, he played the final six minutes of the shortened contest, helping Como preserve their clean sheet in an unusual pre-season encounter.