Inter Milan's hopes of enjoying an untroubled run into the Champions League next season suffered a setback with a shock 2-1 defeat at Cagliari on Friday.
Inter remain in third place but can slip to fourth -- and the last automatic qualifying spot for the Champions League -- if city rivals AC Milan see off Sassuolo at the San Siro on Saturday.
Should fifth-placed Roma defeat Lazio on Saturday, then they will go level with Inter on 47 points.
Inter, still without unsettled striker and skipper Mauro Icardi, slipped a goal down in Sardinia on Friday after 31 minutes when Luca Ceppitelli headed home.
Lautaro Martinez levelled with another header seven minutes later from a cross by former Cagliari player Radja Nainggolan.
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But with half-time approaching, Leonardo Pavoletti restored his team's lead with a smart volley.
Cagliari could have heaped further misery on Inter in stoppage time at the end of the game but Nicolo Barella missed a penalty kick.
Friday's result represented another twist in a rollercoaster season for Luciano Spalletti's side.
After defeats to Torino and Bologna, Inter then put together back-to-back wins over Parma and Sampdoria before being held to a 3-3 draw at Fiorentina after having led 3-1.