Team Sky’s Geraint Thomas took the leader’s yellow jersey as Ireland’s Dan Martin won stage five of the Criterium du Dauphine.
Martin, who rides for Team Emirates, finished four seconds ahead of Welshman Thomas after a late attack on the climb to Valmorel ski resort in France.
Thomas, 32, leads the race by 69 seconds with two stages remaining.
“I’ll enjoy tomorrow, or I’ll try to enjoy it in the jersey and defend it, but it’s super hard,” he said.
“It’s a super hard climbing stage race, even harder on the weekend now.”
Thomas’ fellow Briton Adam Yates finished third to climb to sixth overall, while Martin moved up to 14th, two minutes 26 seconds behind the leader.
Saturday’s 110km sixth stage takes the riders from Frontenex and La Rosiere Espace San Bernardo.
Thomas believes winning the Criterium would surpass his achievements to date, which include wins in both the Paris-Nice and Volta ao Algarve races in 2016, as well as victory in the stage-one time trial in last year’s Tour de France.
“It would be right up there, probably the biggest,” said Thomas.
“Paris-Nice is obviously a big stage race but this one, being so close to the Tour, has got a lot of prestige, so it would be massive.
“I’m not thinking that far ahead even though it’s only two days away – I just worry about tomorrow first.”
Stage five result
1. Daniel Martin (Ire/UAE Team Emirates) 3hrs 21mins 19 secs
2. Geraint Thomas (Wal/Team Sky) +4secs
3. Adam Yates (Eng/Mitchelton-Scott) +15secs
4. Emanuel Buchmann (Ger/Bora-Hansgroheat) +16secs
1. Geraint Thomas (Wal/Team Sky) 17hrs 16mins 53secs
2. Damiano Caruso (Ita/BMC Racing Team) +1min 9secs
3. Gianni Moscon (Ita/Team Sky) Same time
4. Julian Alaphilippe (Fra/Quick-Step Floors) +1min 10secs