Jorge Lorenzo toughed it out to secure a battling fourth place finish in the Austin MotoGP after struggling for fitness as he recovers from a bout of bronchitis.

The Movistar Yamaha rider, who started from the front row in third place, overhauled Bradley Smith at the half-way point and passed Andrea Iannone with four laps remaining to gain another place, finishing outside the rostrum positions at the Circuit of the Americas in Texas.

"It was a very tough race, because physically I wasn't feeling good due to the bronchitis and the antibiotics," Lorenzo said. "But I tried, I fought all the race.

"I was struggling a lot to keep the pace of Valentino and the two Andreas. Finally I think Iannone had more problems on the right side of the front tyre, so I could overtake him and be at least fourth.

"We had tried to modify the setting, to put more front weight to help tyre life and to avoid the graining. I think it helped but we lost traction in most of the corners, probably because of less weight on the rear.

The Spaniard added that it had been the correct decision to select the medium compound front tyre, rather than the hard used by team-mate Valentino Rossi.

"When we tried [the hard] yesterday, it was graining even worse than the [medium] one. Also, Valentino finished worse than my tyre, so for sure the setting that we take was worse for acceleration, but it saved my front tyre. I think it was a good choice, the medium tyre.

"We finished the race in the best way possible given the circumstances. Here and in Qatar two problems occurred that were difficult to overcome but we saved the situations the best we could," added Lorenzo, referring to the issue with his helmet at Losail, which restricted his vision.

"Of course it's not the results we are expecting but we are not so far from the first place in the championship and our time will arrive."

The double premier class champion is optimistic of returning to full fitness in time for round three of the championship in Argentina next weekend and says he has 'high hopes' for a strong result at the Termas de Rio Hondo track.

"I will probably be fit in Argentina. Last year I rode a good race there while I wasn't in the best condition," he said.

"Now that the bike is working better, I hope I will be ready physically. I have high hopes for the race in Argentina and the track is fun to race at."