A poor display from the away side meant it slumped to a well-deserved thrashing in Florence, with the Balkan strike duo doing the damage.
Given an unexpected chance to close the gap on Juventus following the Serie A leaders' 1-0 reverse at Roma, Inter instead contrived to throw away the opportunity thanks to a nightmare first half in Florence. Gaps appeared across the away defense, which Fiorentina gleefully exploited as it poured forward in numbers and with purpose.
Stevan Jovetic almost handed his side the lead less than three minutes into the encounter, latching on to a lofted ball from David Pizarro only to be denied one-on-one with Samir Handanovic, the keeper stopping the Fiore man's effort with his legs.
Jovetic, however, was unbowed. With 13 minutes gone, the forward did brilliantly to nod Manuel Pasqual's cross into the path of Ljajic, who was completely untroubled by any man in white as he got down low to head in from short range.
Inter needed to respond, and finally managed an effort on the Viola net through Zladko Kuzmanovic's speculative shot, but it was Fiorentina which would continue to dominate proceedings. Tenacious play from Alberto Aquilani led to the home side robbing possession on the edge of the Nerazzurri area, and the midfielder laid off to Jovetic who released a stunning strike past Handanovic and further sink the lackluster visiting side.
The only consolation for Inter was that, in truth, the first 45 minutes could have ended a great deal worse. Handanovic was called into action time and again as the Fiorentina front men took target practice at his posts, aided by a back line that had gone missing in action. Borja Valero was denied by the keeper's legs after receiving a cross unmarked at the back post, while Aquilani also forced an excellent save from the harassed Slovenian. While Inter could count itself lucky to be 'only' 2-0 down a vastly improved performance was required after the break if the club wished to take anything from the encounter.
Nothing, however, appeared to change at the start of the second half as Fiorentina continued to take the initiative. Juan Guillermo Cuadrado almost added a third five minutes in as his savage left-footed shot was deflected inches wide of Handanovic's left post to save Inter from what would have been the coup de grace on the evening.
The jubilant home fans did not have to wait too much longer though. A defensive mix up for Inter left Aquilani in possession of the ball, and it was all so simple for the Italian as he threaded through to Jovetic with the heel. Stevan was blissfully free in the area, and had time to take aim and smash the ball past the hapless Handanovic to end Inter's interest in Sunday's contest.
The home team was coasting to victory, but was still in the mood to twist the knife. Nobody in white checked Valero as he marched on goal down the left, and he found Ljajic who was similarly untroubled in bending a lovely effort into the corner of the net. The Nerazzurri were in shambles, and Antonio Cassano could barely muster a celebration for his brilliant long-range consolation as Fiorentina marched to three points.
The loss means Inter remains 11 points shy of Juve at the summit, while also failing to climb above Lazio in Italy's final Champions League spot. The Romans can go four clear of Andrea Stramaccioni's men if they defeat Siena on Monday evening, while Fiorentina is hot on their heels moving just one behind in sixth.