Massimiliano Allegri's decision to rest several of his key stars backfired as Juventus lost ground in the Scudetto race with a shock 3-2 defeat at Sampdoria.
Paulo Dybala and Gianluigi Buffon were among several regulars left out of the starting XI and the Serie A champions paid the price as they conceded three second-half goals.
Gonzalo Higuain and Juan Cuadrado both failed to make the most of earlier chances to leave the door ajar for the home side.
Sampdoria needed no invitation to take advantage as Duvan Zapata crashed in a 52nd-minute header before Lucas Torreira fired home from outside the area to completely swing the momentum.
Gianmarco Ferrari appeared to have put the seal on an emphatic victory when he made it 3-0 with just over 10 minutes remaining, although the Bianconeri mounted a stoppage-time fightback as Gonzalo Higuain scored from the spot after Ivan Strinic was adjudged to have fouled substitute Douglas Costa.
Dybala had also come off the bench in a bid to rescue Allegri's side and the Argentina star fired in a quickfire second to set up a tense final few seconds, but the damage was done.
The defeat leaves Juve four points adrift of leaders Napoli and they could drop to third depending on Inter's result against Atalanta later on Sunday.