Further back, Van Garderen had remounted and got himself into another chasing group, 30 seconds further back from the GC group, before attacking off the front to chase across.
He was just closing in on the cars when he suffered another crash on a roundabout – again remounting and resuming his chase.
Sanchez and Polanc tried to bridge across from the GC group to the three leaders, but they could not close the gap as the leading trio worked well together – holding a 17-second advantage under the flamme rouge.
It was enough time for the front three to stare each other down, constantly delaying their sprint before Mas finally kicked first.
Marczynski had the better sprint, however, and used it to great effect to claim his first Grand Tour stage win aged 33.
Froome finished eighth meanwhile, to ensure he has now worn the red jersey more than any other Brit – overtaking Sir Bradley Wiggins.
Vuelta a Espana 2017: stage six – result
1) Tomasz Marczynski (POL) – Lotto-Soudal – 4.47.02hrs
2) Pawel Poljanski (POL) – Bora-hansgrohe – ST
3) Enric Mas (ESP) – QuickStep Floors
4) Luis Leon Sanchez (ESP) – Astana +8”
5) Jan Polanc (SVN) – UAE Team Emirates – ST
6) Warren Barguil (FRA) – Team Sunweb +26”
7) Giovanni Visconti (ITA) – Bahrain-Merida – ST
8) Chris Froome (GBR) – Team Sky
9) Fabio Aru (ITA) – Astana
10) Jack Haig (AUS) – Orica-Scott
General classification
1) Chris Froome (GBR) – Team Sky – 22.54.38hrs
2) Johan Esteban Chaves (COL) – Orica-Scott +11”
3) Nicolas Roche (IRL) – BMC Racing +13”
4) Tejay van Garderen (USA) – BMC Racing +27”
5) Vincenzo Nibali (ITA) – Bahrain-Merida +36”
6) David de la Cruz (ESP) – QuickStep Floors +40”
7) Fabio Aru (ITA) – Astana +49”
8) Adam Yates (GBR) – Orica-Scott +50”
9) Michael Woods (CAN) – Cannondale-Drapac +1.13
10) Simon Yates (GBR) – Orica-Scott +1.26