Checa looked almost certain to win for the second time this season, only for technical problems to hand victory to Biaggi.
Max Biaggi has won his fifth World Superbike race of the season at Miller Motorsports Park, but only after a cruel technical problem robbed
Carlos Checa of certain victory.
The Spaniard had led from almost start-to-finish on the Althea Ducati, Checa shaking off the attentions of Biaggi at the midway point before pulling out an advantage of almost three seconds.
However, the race would prove just two laps too long for Checa as he coasted off the circuit, promoting Biaggi to a somewhat fortuitous victory.
Aiding his title hopes, Biaggi has pulled back five points over Leon Haslam in the championship fight, the Suzuki rider recovering from a poor start to claim second position, while
Noriyuki Haga was back on the podium in third.
Having been billed pre-race as a straight fight between the Ducati of Checa, who smashed the lap record on the way to pole position, and the Aprilia of Max Biaggi, which had displayed superior advantages through the speed traps, it was little surprise to see both riders leap into the lead early on.
Indeed, while the long run down to the first left-hander did enable Leon Camier to squeeze between the pair on the second RSV-4, Checa needed just one more bend to dispose of the Briton.
Instantly Checa began pressuring Biaggi, but while he would lose ground down the huge home straight – he would average around 16kph slower throughout the race -, he displayed superior confidence through the bends as he simply out-manoeuvred his rival round the outside of Witchcraft on lap two to snatch the lead.
From here, the pair would pull away from third place man Camier, who in turn had a comfortable advantage over the fast-starting Troy Corser.
With the pendulum swinging between the straights and bends as they bunched up and then gapped one another, it took until lap 13 for Checa to pull a second over Biaggi.