For four months, Inter Milan had been pointing to their postponed match at Bologna as a chance to gain ground in the title race.
Yet a goalkeeping blunder handed Bologna a 2-1 win on Wednesday as Inter wasted a lead as well as a chance to reclaim their lead in Serie A.
It left defending champions Inter still trailing city rivals AC Milan by two points with four matches remaining.
Reserve goalkeeper Ionut Radu was thrust into action for the first time in nearly a year following a back problem to Samir Handanovic and was to blame for Bologna’s winner.
Attempting to clear following a throw in, Radu instead kicked the ball towards his own net and Bologna’s Nicola Sansone had the final touch to make sure it went in.
Former Inter Milan striker Marko Arnautovic headed in the equaliser for Bologna after Ivan Perisic had put Inter ahead early on.
The match had been postponed from January due to a coronavirus outbreak within Bologna’s squad.
Fiorentina and Atalanta also wasted opportunities to boost their chances of qualifying for Europe in two other postponed matches.
Seventh-place Fiorentina were beaten for the second game running, being hammered 4-0 at home by Udinese.
Pablo Mari, Gerard Deulofeu, Walace and Destiny Udogie scored for 12th placed Udinese.
Eighth-placed Atalanta had to scramble for a remarkable 4-4 draw at home against Torino, with Luis Muriel converting his second penalty of the night for an 84th-minute equaliser.