Reggina's hopes of avoiding relegation from Serie A suffered a hammer blow when they were thrashed 5-0 at Sampdoria yesterday.
The bottom side, who picked up valuable points in recent weeks, lost Carlos Valdez to a 19th-minute red card and never recovered.
Reggina are three points from safety and have three games remaining while their rivals have four.
Mid-table Sampdoria left playmaker Antonio Cassano on the bench with one eye on Wednesday's Italian Cup final against Lazio but still romped to victory.
Daniele Dessena netted twice while Gennaro Delvecchio, Guido Marilungo and Italy striker Giampaolo Pazzini also struck.
Lazio warmed up less well for Wednesday, losing 3-1 at home to Udinese and seeing their outside hopes of a Europa League berth through Serie A all but vanish.
Italy striker Fabio Quagliarella, heavily linked in the media with Inter, sealed Udinese's win with an 86th-minute penalty before Lazio's Cristian Brocchi was dismissed.
Inter could win the title today if they win at Chievo and second-placed Milan lose at home to Juventus.