Valentino Rossi says there is no danger of him getting complacent even though he has edged away from his championship rivals in recent weeks.
There had been a three-way tie at the top of the standings following the Catalunya Grand Prix, but since then Casey Stoner has dropped away as he struggled with illness, and Rossi has defeated his Yamaha team-mate Jorge Lorenzo at every race, putting him 14 points clear in the standings.
While satisfied with his recent form, Rossi said he was taking nothing for granted until the title was won.
"I'm so happy because since Barcelona I've come back very strong. A good result in the last race," he said.
"But anyway the advantage in the championship is tight. I'm arriving from some positive results but we're only just over halfway [through the season] so I have to stay concentrated and work in the same way to try to arrive in front at the end."
The last two seasons have seen a single rider make a clear break in the championship by the halfway point, with Stoner dominating in 2007 and Rossi doing likewise last year.
Rossi believes 2009's more open competition is largely due to the end of the tyre war giving the whole field equal rubber, allowing riders like Lorenzo and Honda's Dani Pedrosa back into the fight after they had trailed Rossi and Stoner's Bridgestone-shod bikes for much of 2008.
"Firstly the mono tyre levelled the performance of the top guys a lot," said the reigning champion. "Also some other riders sometimes are in the fight, but usually we have four that are in good shape and have the best bikes on the grid.
"One mistake from me and Jorge [Lorenzo], but Stoner always arrives at the end of the races, so for this reason the championship is very tight."