Dani Pedrosa was in contention for his second MotoGP victory in a row for the first half of Sunday's US Grand Prix, until his weakened physical conditions began to take its toll.
Pedrosa took second from Repsol Honda team-mate Casey Stoner at the start, and kept within touch of Yamaha's race leader Jorge Lorenzo for the first half of the 32-lap race.
But by then Pedrosa, who missed three races after fracturing his collarbone in May, felt physically 'finished'.
The former US GP winner was overtaken by eventual race winner Stoner on lap 18 of 32 and went on to finish almost four-seconds from runner-up Lorenzo.
"I'm very happy with another podium, the second after my come back from injury," said Dani. "I couldn't have predicted this result before coming to Laguna, because I knew it would be physically very tough for me and it has been great to keep up with the pace of Casey and Jorge in these past two races.
"Today, by the middle of the race, I was very tired, almost finished, I couldn't get my left arm strong enough and here at this track you don't rest for a moment, so I had to drop. It's been quite difficult to set up the bike this weekend, I had a lack of grip generally, but the team worked very well.
"Now we have some holidays and it will be good for me to have some days off to rest and relax my muscles and be back training to arrive fully fit in Brno".
Pedrosa's fifth podium of the season means he is now back ahead of Valentino Rossi for fourth in the championship.