But Boss described it as a minor incident.
"It was a little bump in the road," he said.
Boss required major surgery on his shoulder after he came off group one winner Crystal Lily when she collapsed and died at trackwork in September.
It was the second serious injury for Boss who spent months in a halo brace after breaking his neck in a fall in Macau in 2002.
The following year he partnered Makybe Diva to the first of three Melbourne Cups.
There was no need for the camera in the feature staying event at Werribee with Apprehend a decisive all-the-way winner of the listed Werribee Cup (2600m).
Ridden by Craig Newitt, Apprehend held Hanks at bay by three lengths with Hiphopopotamus another half length third.
"He relaxed well underneath me," Newitt said.
"He needed to get going rather than them jump on top of him. He can sustain a long run and he held on well."
Apprehend is trained by Tony Vasil at Caulfield and the win was his eighth from 50 starts and his first at stakes level.
