In what has been a largely disappointing campaign so far for Milan, there may yet be light at the end of the tunnel as their end-of-season resurgence under Clarence Seedorf continued at San Siro on Sunday.
Their latest victory has taken them to within five points of rivals Inter, who occupy the last guaranteed UEFA Europa League spot, although sixth place could also still provide a berth in Europe's secondary competition should Coppa Italia finalists Napoli and Fiorentina finish in the top five.
Riccardo Montolivo, who netted in Milan's 3-1 victory at Catania earlier this season, scored the game's only goal in the 23rd minute thanks to a superb long-range effort.
And while a second goal proved elusive, Milan controlled the match and were aided by Fabian Rinaudo's late red card – given after an over-the-ball lunge on Philippe Mexes saw him booked for a second time.
Barrientos' curling 25-yard effort awoke Milan from their slumber and Adil Rami went close to giving them the lead, flicking Kaka's whipped free-kick from the left over the bar.
Balotelli could have doubled their lead, only for team-mate Andrea Poli to take the ball away from him following Taarabt's dangerous cross.
Defender Mexes almost scored an outrageous goal, with the centre-back's acrobatic scissor kick going over from Balotelli's dinked free-kick, and Nigel De Jong was then denied by Catania goalkeeper Mariano Andujar.
Milan could not find the all-important second goal but Catania's hopes of salvaging a draw were dealt a blow with 11 minutes left as Rinaudo was given his marching orders.
