Valentino Rossi said he cruised to the finish at Indianapolis because he feared a repeat of his Laguna Seca accident as Ducati again struggled in hot conditions in America.
Rossi finished nearly a minute behind winner Dani Pedrosa in seventh place, 27 seconds adrift of nearest rival Stefan Bradl, and not far ahead of the CRT riders.
"In the end, the position is not bad, but unfortunately I was very slow in the race," Rossi told the official MotoGP website.
"After this morning we expected a bit better. I was not so bad in the cold conditions of the morning but I suffered a lot in the hot in the afternoon. It also happened yesterday."
He said it had been too risky to try and push any harder in the race, so chose to settle for a points finish
"In the beginning I could stay with the guy in front, but I had two big moments so I decided just to arrive at the end and not to do the same mistake as at Laguna Seca," Rossi said.