Bristol will be without Wales internationals Gavin Henson and Ryan Jones for next Wednesday's Greene King IPA Champonship play-off final second leg against Worcester.
Bristol rugby director Andy Robinson initially said that centre Henson suffered a broken foot during the second-half of a 29-28 first leg defeat at Ashton Gate, but then later confirmed it to be a fractured shin.
And flanker Jones suffered a shoulder injury that will also rule him out of the Sixways return encounter.
Henson had delivered an impressive performance for Bristol, executing a superb tactical kicking display, but he went down in open play midway through the final quarter and was carried off.
Worcester, meanwhile, crept into pole position for a quick-fire return to top-flight English rugby after they edged an absorbing and dramatic encounter.
Relegated from the Aviva Premiership last term, Worcester will head into the return encounter with a narrow lead following substitute hooker Niall Annett's injury-time try that Ryan Lamb converted.
First-half touchdowns by flanker Sam Betty, wings Cooper Vuna and Tom Biggs, plus a penalty try, earlier put Worcester narrowly on top, with number eight Mitch Eadie and a double from wing David Lemi delivering Bristol's tries, while Henson booted 10 points before substitute Nicky Robinson slotted a late penalty.
But given that Bristol had two players sin-binned during the first half and Warriors fly-half Lamb landed only two kicks - both of them conversions - from six shots at goal, it could easily have been a far worse night for the home team in front of a 12,000 crowd.
Reflecting on a tense win, Worcester rugby director Dean Ryan said: "It's half-time in the tie and it is pretty tight.
"It was a bold move for Bristol to go for home advantage and I think they wanted to put it on us in the first 40 minutes, so we knew we had to come out and really attack it and I thought the lads did a great job.
"In the second half, I thought we stood pretty firm. Bristol threw everything at us. We couldn't get field position and Henson's kicking was killing us, but we stood firm and saw it out.
"To finish like we did with a little bit of a show of defiance I thought was outstanding. We are effectively on level terms but we are at Sixways next week and let's see how the bodies fare over the next few days because that was full-on.
"It is going to be a straight shoot-out now, and whoever wins next Wednesday is in the Premiership."
And Bristol boss Robinson added: "It ebbed and flowed. It was a fantastic game of rugby and a real rollercoaster ride for the supporters.
"I though that tactically Worcester played well, but we got ourselves back in the game and defended heroically. The second-half performance was very pleasing.
"To lose a lineout right at the end put us under pressure but credit to Worcester, they kept their cool and scored a good try.
"We have got to go out and win the game next week and we believe we can go out and do that.
"What a statement from both sides. I thought it was a fantastic game. One team is going to be happy next week and one is going to be disappointed.
"We know what we have to do next Wednesday. We knew at the end of this game there would be a second half to be had and we are looking forward to the battle."