Simon Yates held on for victory in the Tirreno-Adriatico after withstanding a challenge in Monday’s final stage from Geraint Thomas, who finished second.
Mitchelton-Scott’s Yates started the individual time trial in Italy with a 39-second lead over his fellow Briton.
Thomas clocked the fourth best time but his 22-second gain on Yates was only enough for second place overall.
The time trial was won by Thomas’ Ineos Grenadiers team-mate Filippo Ganna, with another, Rohan Dennis, third.
Yates was 18th but his time of 11mins 32secs around the 10.1km course in San Benedetto del Tronto, Italy, was enough to secure victory for the 2018 Vuelta a Espana champion.
His twin brother Adam, who is competing at the Tour de France, lost this race by a single second following a time trial to finish last year.
“I’m really happy. It’s my only stage [race] win outside of La Vuelta so I’m just happy I could finish off the job of the team,” said Yates.
“They did a fantastic job all week. Today was up to me and I was able to hang on so I’m really happy.
“I was very aware [Adam] lost by such a little, less than a second, so I was nervous but I can only do my best and I’m happy to hold on.”
For Thomas, meanwhile, this was a promising performance as he prepares for next month’s delayed Giro d’Italia.
The Welshman has chosen to concentrate on the Italian Grand Tour this year instead of the Tour de France, which is in its final week.
“It was good. I didn’t have another 17 seconds in me but I definitely feel like I had a bit more in there,” said Thomas.
“It’s really encouraging after eight days’ racing, especially after the start of 2020. I feel a lot better now.
“I never thought it was quite possible to get 40 seconds in 10km [to catch Yates] – that’s a hell of a lot – but I’m happy with how that went.”
Thomas’ Ineos Grenadiers team-mate and four-time Tour champion Chris Froome was 79th in Monday’s time trial and finished down in 91st place overall.
Stage eight result
1. Filippo Ganna (Ita/INEOS Grenadiers) 10mins 42secs
2. Victor Campenaerts (Bel/NTT Pro Cycling) +18secs
3. Rohan Dennis (Ita/INEOS Grenadiers) +26secs
4. Geraint Thomas (GB/INEOS Grenadiers) +28secs
5. Tobias Ludvigsson (Swe/Groupama-FDJ) +33secs
6. Benjamin Thomas (Fra/Groupama-FDJ) +34secs
1. Simon Yates (GB/Mitchelton – Scott) 32hrs 07mins 34secs
2. Geraint Thomas (GB/INEOS Grenadiers) +17secs
3. Rafal Majka (Pol/BORA – Hansgrohe) +29secs
4. Wilco Kelderman (Ned/Team Sunweb) +56secs
5. Aleksander Vlasov (Rus/Astana Pro Team) +58secs
6. Fausto Masnada (Ita/Deceuninck – Quick-Step) +1min 18secs