Jorge Lorenzo took his first MotoGP victory since wining the 2010 world championship at Estoril on Sunday, when Yamaha completed a clean sweep of all three titles – Riders', Teams' and Constructors' - for the third year running.
The achievement marks the first time since the Triple Crown's inception that any manufacturer has won it three times in a row.
Lorenzo's eighth victory of the season, but first since Brno in mid-August, also continued a perfect personal record at Estoril, where he has won from pole on all three MotoGP appearances.
But the victory was far from straightforward, being on an 'unknown' dry track after a weekend of rain.
Lorenzo made a strong start from pole, taking the lead into the first corner before briefly relinquishing it to Ducati's Nicky Hayden.
Lorenzo's Fiat Yamaha team-mate Rossi made a play for the lead on lap four, relegating the Spaniard to second until lap 17 of 28, where a decisive out-braking manoeuvre saw Lorenzo retake the lead.
The 23-year-old then pulled a massive 8.629sec advantage over Rossi, making it the biggest victory margin of the year.
"On the warm-up lap I could see there were still a few wet parts and I knew that I was going to have to be careful at the beginning," recalled Lorenzo. "I got a great start and was in the lead but eventually Valentino overtook me and then off he went. He had a better pace than me then and I couldn't go with him.
"As the track got drier I found my pace improving and then step-by-step I closed the gap and was able to get past him. At that point I felt really good and I am so happy to win for the third time here at Estoril.
"It was a long time since I have won but my confidence has remained high and I haven't been worried. I knew I could win here at my favourite track. We also confirmed the Triple Crown for Yamaha today so well done to the whole team for this victory."
"This is victory number eight and after a few races of not winning we are happy to be first again!" added team manager Wilco Zeelenberg. "We need to keep our focus for Valencia because it would be great to finish this fantastic season with one more win."
The Valencia finale takes place this Sunday.