With Checa's Bridgestone tyres expected to offer a more consistent race pace than the rival Michelins, it looked as though Rossi could find his podium position in jeopardy - but soon after the halfway stage the Italian seemed to find a second wind and was able to creep away from Checa, while reducing the gap to Hayden to below five-seconds.
Between laps 20 and 23 Rossi then turned up the heat even further, gaining further chunks of time on the top two to reduce the deficit to just 3.6secs - as his lead over Checa drew to almost six-seconds - if he continued at that rate Rossi would easily catch Hayden and Melandri.
But the pair responded, matching Rossi's lap times for the next four circulations - and when the seven-times world champion was still 3.4secs from Hayden with three laps to go, even his most hardened supporters must have realised that he would need a miracle.
With Rossi, as hard as it is to believe, realistically out of contention - attention switched to which of the top two was going to win the race: Melandri had led right from turn one, without putting a wheel wrong, but Hayden had been with him every step of the way and must have gained a good idea of where a pass could be made.
As the penultimate lap began, Melandri played his cards first by attempting to shake the American with a flat out attack. The tactic looked like it might work as he took a 0.35secs lead over Hayden into the start of the final lap of 2005, putting the #69 just out of range.
But through the middle sector of Nicky gained that ground back and was on Melandri's rear Michelin as the Italian headed for the fast, off camber, left hander that leads into the tight final turn.
Then, as the pair slid their rear wheels over the crest, Melandri bobbled slightly - a mistake that looked like it could hand Nicky the race - certainly Melandri seemed to think so and responded with a tight defensive line into the last turn.
Realising this, Hayden stayed wide and cut back in on the exit - with the aim of out-dragging his rival on the run to the chequered flag - but Melandri kept his composure and a tidy exit allowed the young Italian to propel his Movistar machine clear of the Kentuckian for victory by just 0.097secs.
Melandri appeared rightfully delighted with his second win in as many starts - his only mistake coming shortly after when he dropped his RCV while celebrating with the fans - while Hayden, who had been left punching the fuel tank with frustration as he crossed the line, took a few corners before regaining his usual friendly personality.
Melandri's win also confirmed his second position in the 2005 riders' world champion, albeit some 147-points behind Rossi, marking an amazing jump in performance for a rider who was just 15th in the 2003 championship and 12th in the 2004 standings.