MILAN - Leaders Inter Milan kept up their relentless pursuit of a fourth straight Serie A title when Zlatan Ibrahimovic scored twice in a 2-0 home win over Fiorentina on Sunday. Inter, knocked out of the Champions League by Manchester United on Wednesday, were again not at their best and also had goalkeeper Julio Cesar to thank for reasserting their seven-point advantage at the top. Ibrahimovic was fortunate to score on 11 minutes when he nodded in a loose ball after Fiorentina keeper Sebastien Frey had punched Mario Balotelli's free kick against the Swede. The striker, who again let himself down on the big occasion at Old Trafford, netted a fierce free kick in stoppage time moments after Jose Mourinho had been sent from the dugout for arguing. "We are suffering every game because every game is difficult and each year it gets tougher," Ibrahimovic told Sky television. Second-placed Juventus beat Bologna 4-1 on Saturday to put pressure on Mourinho's side. AC Milan, in third, remained 12 points behind their city rivals after Filippo Inzaghi netted his 300th career goal when he struck twice in a 5-1 triumph at Siena on Sunday. The 35-year-old tapped in David Beckham's corner to put the visitors 2-0 up at the end of the first half and tucked home Andrea Pirlo's pass to make it 4-1 and bring up the 300. Brazil striker Alexandre Pato also netted twice after Pirlo had started the rout with a seventh-minute penalty. Massimo Maccarone's goal was hardly a consolation to mid-table Siena. ABBIATI OUT The day was not perfect for Milan, however, with substitute Kaka returning from a month out with a foot injury before having to go off with a minor ankle problem. Goalkeeper Christian Abbiati also suffered a knee ligament injury. In Sunday's other standout Serie A games, faltering Napoli were held 1-1 at bottom side Reggina in Roberto Donadoni's first game in charge since replacing the sacked Edy Reja. The former Italy coach, dismissed after a poor Euro 2008, watched as Bernardo Corradi easily beat his side's offside trap to score midway through the first half but Ezequiel Lavezzi grabbed a point when he slammed in on 64 minutes. Lecce's new coach Luigi De Canio got off to a worse start with his second-bottom side losing 5-2 at Palermo while Giuseppe Mascara scored from 40 metres in Catania's 1-1 draw at Udinese. Lazio were humbled 3-0 at home by struggling Chievo Verona, who climbed out of the drop zone and were replaced by Torino, 2-0 losers at Atalanta. Sixth-placed AS Roma, hampered by injuries after Wednesday's Champions League elimination by Arsenal, drew 2-2 at Sampdoria despite having defender Marco Motta sent off in the second half.