Italian Gianluca Brambilla and Russia's Ivan Rovny have been disqualified from the Vuelta a Espana after coming to blows during Monday's 16th stage.
Both men landed punches on each other as they rode among a breakaway group of 13 riders on the 160.5km stage from San Martin del Rey Aurelio to La Farrapona.
Alberto Contador won the stage after seeing off Chris Froome on a summit finish to increase his overall lead to 96 seconds over Alejandro Valverde.
Briton Froome finished 14 seconds back.
Tinkoff-Saxo's Rovny needed a new pair of sunglasses from his support team after they were broken in the altercation with Brambilla.
Omega Pharma-Quick-Step rider Brambilla, 27, was in a leading group when he was forced to quit after a short discussion with race organisers, raising his arms up in the air in frustration.
A short time later Rovny, 26, also dropped out of the main pack after being told of his punishment by his team.
Brambilla apologised for his actions in a tweet posted later on Monday.
"I'm sorry. This situation shouldn't have happened. For my part in it, I apologize to #OPQS, race organizers, and the fans. #sadday," he wrote.
Contador's win saw him move a huge step closer to claiming his third Vuelta victory.
The Spaniard was able to go with Froome when the Team Sky rider made his move with just four kilometres remaining of the long climb to the finish line.
The two managed to distance themselves from the chasing Valverde and Joaquim Rodriguez but it was two-time Tour de France winner Contador who had the stronger finish.
"Today was a very good day for us," said Contador. "I had the power I needed, I managed to keep going with the pace imposed by Froome and when I saw my opportunity I took advantage of it."
Froome's strong ride saw him close to within three seconds of second-placed Valverde in the general classification.
After Tuesday's rest day, the race returns with a flat 190.7km ride from Ortigueira to A Coruna on Wednesday.
Stage 16 result:
1. Alberto Contador (Spa/Tinkoff - Saxo) 4:53:36"
2. Chris Froome (GB/Team Sky) +14"
3. Alessandro De Marchi (Ita/Cannondale) +48"
4. Alejandro Valverde (Spa/Movistar) +53"
5. Joaquim Rodriguez (Spa/Katusha) +57"
6. Fabio Aru (Ita/Astana) +1:06"
7. Daniel Martin (Irl/Garmin) +1:12"
8. Robert Gesink (NED/Belkin) +1:22"
9. Samuel Sanchez (Spa/BMC Racing) +1:43"
10. Ryder Hesjedal (Can/Garmin) +1:48"
Overall classification after stage 16:
1. Alberto Contador (Spa/Tinkoff-Saxo) 63hrs 25mins 00secs
2. Alejandro Valverde (Spa/Movistar) + 1min 36secs
3. Chris Froome (GB/Team Sky) +1min 39secs
4. Joaquim Rodriguez (Spa/Katusha) +2mins 29secs
5. Fabio Aru (Ita/Astana) +3mins 38secs
6. Daniel Martin (Irl/Garmin) +6mins 17secs
7. Robert Gesink (NED/BKN) +6mins 43secs
8. Samuel Sanchez (Spa/BMC Racing) +6mins 55secs
9. Warren Barguil (Fra/Giant) +8mins 37secs
10. Damiano Caruso (Ita/Cannondale) +9mins 10secs