The 20th stage saw Enric Mas take the race win on the mountainous stage to to Coll de la Gallina, with Yates effectively sealing victory by crossing the line in third.

The Briton now leads Mas, who moved into second following his triumph today, by one minute and 46 seconds going into tomorrow's processional stage in Madrid.

Two Spanish riders battled it out for the stage win as Mas took on Miguel Angel Lopez on the final climb.

Riding for Quick-Step Floors, Mas claimed his first stage victory in dramatic style, edging out his compatriot after 97.3km.

Yates dropped 23 seconds to the leaders but maintained his position at the top of the standings.

With a comfortable advantage over Mas, the British rider will be crowned overall winner tomorrow barring any diastrous outcome.

The Mitchelton-Scott rider was third to cross the line after he lost contact with Lopez and Mas with six kilometres to go.

"As they say, sometimes attack is the best form of defence," said Yates.

"I gave it everything I had and thankfully it was enough."

Elsewhere in Madrid, Team Sunweb won the team time trial first stage of the Women’s World Tour in 17min 40sec.

Wiggle Highs were second in 17mins 58secs with Mitchelton Scott third.

Canada’s Leah Kirchmann, American Coryn Rivera, Dutch rider Ellen Van Duk and Germany’s Liane Lippert are the top four, riding for the Sunweb team.

Kirchmann will be the race leader going into tomorrow’s stage.

The Madrid Challenge second stage will be a 100.3km ride.