Chelsea manager Thomas Tuchel and Southampton counterpart Ralph Hasenhuttl bemoaned key video assistant referee interventions after the Blues won 3-1 against their 10-man opponents at Stamford Bridge.
Both decisions were made after input from VAR Mike Dean - Werner's goal had been awarded by on-field official Martin Atkinson, who later chose only to book Ward-Prowse for his sliding tackle.
Hasenhuttl said he felt "relatively clear" Ward-Prowse would be sent off once Dean had instructed Atkinson to review the midfielder's challenge.
"It's always a little bit of a problem when we know Mike Dean is VAR because we have not had a good history with him to be honest," Hasenhuttl told BBC Radio 5 Live.