Rome - Spanish climber Mikel Landa crowned a marathon six-hour slog with a majestic late charge to clinch victory at the summit finish on stage four of the Tirreno-Adriatico on Saturday.

Recently signed with Movistar, the former Sky man Landa timed his run late and finished the day in a strong position to challenge for the overall victory, trailing new blue jersey holder Damiano Caruso by 20 seconds.

The stage was marked by overnight leader Geraint Thomas of Sky suffering an untimely mechanical problem and having to change bikes on the final climb, he lost 40 seconds on the day while his muted team leader Chris Froome was 1:10 off the pace on Saturday too.

The race also suffered the loss of Giro d'Italia winner and world champion Tom Dumoulin, who fell and pulled out early and was later reported to have suffered only cuts and bruises.

For the pure climbers, Dumoulin's demise takes much of the fear out of Tuesday's final-day time-trial and the effects that would have on the overall standings.

Landa took 6:22:13 to complete the challenging stage by outsprinting Rafal Majka and George Bennett to the line.

"I'm in a new team. I'm in good shape and when you start like this in a new team I think that it gives you more confidence," said the 28-year-old, who many pundits feel could win a Grand Tour.

In a chasing group, six seconds adrift, Italy's Fabio Aru and French hope Romain Bardet kept their hopes alive.

Sunday's stage also culminates in a summit finish at Filottrano.

Overall standings

1. Damiano Caruso (ITA) BMC Racing Team 17hrs 14mins 49sec, 2. Michal Kwiatkowski (POL) Team Sky at 01sec, 3. Wilco Kelderman (NED) Team Sunweb 11, 4. Mikel Landa (ESP) Movistar 20, 5. Geraint Thomas (GBR) Team Sky 26, 6. Rigoberto Uran (COL) EF-Cannondale 31, 7. George Bennett (NZL) LottoNL-Jumbo 33, 8. Davide Formolo (ITA) Bora-Hansgrohe 34, 9. Tiesj Benoot (BEL) Lotto Soudal 36, 10. Domenico Pozzovivo (ITA) Bahrain-Merida 41.

Selected: 

12. Fabio Aru (ITA) Team Emirates 45sec, 13. Romain Bardet (FRA) AG2R at 50,  15. Chris Froome (GBR) Team Sky 59, 16. Vincenzo Nibali (ITA) Bahrain-Merida 1min 01sec