Marco Simoncelli, who had been just 13th in the MotoGP standings after round three in Estoril, moved to within striking distance of seventh-placed Nicky Hayden with a fourth place finish at Aragon.
The San Carlo Honda Gresini rider looked on target for his second podium of the season when he took third place on lap 9 of 23, but a mistake soon after dropped him back to fifth.
The Italian then regained a place by overtaking a fading Ben Spies for a second and final time on lap 17.
“I am pleased with this result - we had to grit our teeth and I'm sure that even without the mistake I wouldn't have been challenging for the podium anyway. Lorenzo was faster than me on used tyres so no complaints there," said Simoncelli.
"I didn't get a great start but I managed to get into my rhythm quickly and make some passes to get up to third place. From the tenth lap onwards the tyres really dropped off and then again after another five laps, although Spies was in even worse shape than me so I was able to fight back to fourth.”
Simoncelli is now just eight points from Hayden (Ducati) in the championship. Former 250cc world champion Simoncelli finished eighth in his rookie 2010 season.
Team-mate Hiroshi Aoyama, who has a lower satellite-spec Honda, crossed the line in eleventh - after forming part of an entertaining three-way battle for ninth in the closing stages.
”It was a nice race and a fun battle with Rossi and Crutchlow," said Aoyama. "The final position isn't great but I am happy with the way I rode in difficult conditions, with much less grip than yesterday which made it tough. Valentino, Cal and I passed each other a few times and it was great fun. Now I am hoping to put up a much stronger performance at our home GP.”
Simoncelli is expected to be confirmed as a 2012 Gresini Honda MotoGP rider during the forthcoming Motegi weekend, while Aoyama's future is less clear.