Fly-half Freddie Burns was sent off for a dangerous tackle during his first start for Bath just minutes after creating a bonus point try in the 29-13 Aviva Premiership win against Worcester.
The 27-year-old was initially shown a yellow card after up-ending Worcester wing Josh Adams in the 63rd minute before referee Luke Pearce produced a red after taking another look at replays with TV match official Graham Hughes.
As Bath set about defending a 26-13 lead a man short for the last 17 minutes, they had lively centre Ben Tapuai carried off on a stretcher after a long stoppage. He had taken an accidental knee to the head and was eventually taken away in an ambulance.
Tapuai was one of Bath's try scorers along with Aled Brew (two) and Jonathan Joseph, and Burns had added three conversions before replacement Josh Lewis kicked a late penalty.
Worcester's points came from tries by wing Dean Hammond and fly-half Jamie Shillcock, who kicked a penalty and conversion.
Shillcock missed an angled penalty from 50 metres early on before Joseph scored a long-range try after having a clearance kick charged down. Fortunately, Tapuai was on hand to return the loose ball to the Lions centre who raced away to score in the right corner, Burns adding the conversion.
While Worcester's best work was undone by handling errors, Bath's problem was discipline and that allowed Shillcock to make the score 7-3.
Worcester conjured a smart backline move in the 22nd minute as Hammond came off his wing to brush past Brew for an unconverted try.
As Bath lost hooker Jack Walker to a head injury, Brew made amends by finishing off a long spell of Bath pressure on the half-hour mark with a straightforward finish in the corner.
Bath continued to concede penalties but dazzling skills from flanker Zach Mercer unlocked the visitors' defence, creating a try for Tapuai on the stroke of half-time. Burns added the conversion for a 19-8 lead.
Worcester took up the challenge after the restart with a try by Shillcock and did well to defend at the other end from a five-metre scrum but it was now one-way traffic.
Just short of the hour, Tapuai ran straight and hard to set up a ruck under the posts and Burns found Brew with a long cut-out pass before adding a difficult conversion.
Replacement fly-half Lewis's penalty put them three scores ahead with five minutes to play.