Irishman Sam Bennett won the fifth stage of the Tour of Britain with a sprint finish into Caerphilly but Sir Bradley Wiggins retained the overall lead.
The An Post-Chain Reaction rider out-sprinted Michal Golas (Omega Pharma-Quickstep) and Martin Elmiger (IAM Cycling) after a group of riders pulled clear on the second climb of the category one mountain in Wales.
Ian Stannard (Team Sky) led team-mate and gold jersey-holder Wiggins and, by keeping the group together, successfully helped preserve the four-time Olympic gold medallist's 37-second lead.
Stannard is second in the general classification and leads Switzerland's Elmiger by six seconds.
Bennett - a protege of Irish cycling great Sean Kelly - completed the 177km ride from Machynlleth to Caerphilly in four hours 35 minutes and 28 seconds.
The 22-year-old, who was beaten to the line by Gerald Ciolek (MTN-Qhubeka) in Kendal on stage two, launched an attack from the middle of the group on Caerphilly Mountain having already conquered Cwm Owen and the Brecon Beacons.
After clinching his first career stage victory, the Belgium-born rider told britishcycling.org.co.uk: "It was a real hard fight coming into the finish but I knew if I hung on up the climb that I would recuperate quick enough for the sprint and I just hung in.
"It was a bit of a gamble going into the last corner - I went a bit wide - but I had enough acceleration to take the win."