Chad Marshall leaves Sounders training in ambulance

A season that has been frustratingly defined by injuries appears to have taken yet another turn for the worse. The latest victim is Chad Marshall, who was taken from Sounders training in an ambulance after apparently suffering some kind of neck injury.

Chad Marshall is being taken from Sounders training via ambulance. Trainers had been supporting his head and neck

— Matt Pentz (@mattpentz) September 30, 2015

Marshall has been lying prone on the field since going down. No sign of arm or leg movement. Didn't see the initial incident

— Matt Pentz (@mattpentz) September 30, 2015

Sounders calling practice early. Marshall has been loaded into the ambulance with arms folded across his chest

— Matt Pentz (@mattpentz) September 30, 2015

The three-time MLS Defender of the Year has a history of concussions, most recently missing about 10 games in 2012 when he was with the Columbus Crew. Although Marshall has dealt with various injuries since coming to the Sounders, concussions have not followed him here. But given his history, it's understandable that the Sounders would proceed with immense caution.

At the same time, all of this suggests the injury is potentially quite serious. Training is rarely called early and it is even more rare for a player to leave in an ambulance.

The best-case scenario likely involves Marshall missing at least Sunday's LA Galaxy match. If he were to be declared out for the season, Marshall would be the second Sounders center back to be out for the season. Roman Torres recently underwent ACL surgery and is expected to be out 6-9 months.