  We revisit the Saffman-Taylor experiment focusing on the forced-imbibition
regime where the displacing fluid wets the confining walls. We demonstrate a
new class of invasion patterns that do not display the canonical fingering
shapes. We evidence that these unanticipated patterns stem from the
entrainement of thin liquid films from the moving meniscus. We then
theoretically explain how the interplay between the fluid flow at the contact
line and the interface deformations results in the destabilization of liquid
interfaces moving past solid surfaces. In addition, this minimal model conveys
a unified framework which consistently accounts for all the liquid-entrainment
scenarios that have been hitherto reported.
