French league leader Lens was stunned by three second-half goals as Monaco came from behind to win 3-2 to give Paris Saint-Germain the chance to go top on Saturday.
Florian Thauvin put Udinese ahead after 22 minutes but Alessio Romagnoli earned the draw ten minutes later.
Inter Milan saw off Como 2-0 on Monday to stretch their unbeaten run in Serie A to 11 games and move back to within three points of leaders Atalanta.