Last updated on .From the section Cycling

Thomas took a decisive step towards overall victory with a fine second place in Friday's mammoth mountain stage

Tour de France, stage 20 Coverage: Live text commentary on the BBC Sport website from 13:00 BST. Updates on BBC Radio 5 live from 15:00 BST

Britain's Geraint Thomas can effectively secure victory in the 2018 Tour de France on Saturday.

The Welshman goes into the penultimate stage, a 31km individual time trial, leading Dutchman Tom Dumoulin by two minutes and five seconds.

Tour convention dictates that the wearer of the yellow jersey is never attacked on the race's final stage.

So if Thomas is still leading after Saturday he will just have to cross the line in Paris on Sunday to win.

The 32-year-old would be the third Briton to win the Tour de France, after fellow Team Sky riders Sir Bradley Wiggins and defending champion Chris Froome.

Four-time champion Froome is currently fourth, two minutes and 37 seconds behind Thomas.

An unassailable lead?

Saturday's stage 20, a hilly 31km time trial, separates Thomas - who won the British time trial title last month - from victory in the Tour, but he will face a stiff challenge from the three riders immediately behind him in the overall standings.

Dumoulin, Primoz Roglic and Froome finished first, second and third in the 2017 world time trial championships.

World champion Dumoulin is two minutes, five seconds behind, with Slovenia's Roglic 19 seconds back from the Dutchman and Froome a further 13 seconds in arrears.

The riders will go out in reverse order, with Thomas last to start as race leader.

He will start his time trial at 15:29 BST - there will be live coverage on the BBC Sport website from 13:00 BST plus commentary on BBC Radio 5 live.

Froome heads out at 15:23, two minutes before Roglic, with Dumoulin the penultimate rider down the start ramp at 15:27.

"I'm certainly in a good position but I'm still trying not to get carried away and think about winning the yellow jersey," Thomas told BBC Sport.

"As soon as you take your eye off the ball, you can slip up. I've got a two-minute advantage but still need to ride well on Saturday. I hope it's enough."

Thomas is Cavendish's 'one to watch'

The profile of stage 20's individual time trial

In his stage-by-stage guide for the BBC Sport website Mark Cavendish, who has won 30 stages on the Tour de France during his career, picked Thomas as his potential winner of the stage.

Cavendish said: "It's a mixture of ups and downs on technical roads. It's not going to be someone who can only mash a big gear who is going to win this.

"It's going to be someone that can make a plan and stick to that. A lot of guys will go off hard and with a little kick in the last 3km are likely to lose a lot of time even though it's less than a kilometre long."

General classification after stage 19:

1. Geraint Thomas (GB/Team Sky) 79hrs 49mins 31secs

2. Tom Dumoulin (Ned/Team Sunweb) +2mins 05secs

3. Primoz Roglic (Slo/Team LottoNL-Jumbo) +2mins 24secs

4. Chris Froome (GB/Team Sky) +2mins 37secs

5. Steven Kruijswijk (Ned/Lotto NL-Jumbo) +4mins 37secs