Bristol overcame a 15-point first-half deficit to beat local rivals Bath 40-20 and secure a Premiership play-off spot.

Nathan Hughes' score and a penalty try either side of half-time got Bristol back into it, before Max Malins and Charles Piutau earned a bonus point.

Watson got a second, but Bath prop Tom Dunn was sent off and Ben Earl and Malins went over against 14 men.

The victory was Bristol's biggest Premiership win at The Rec and adds to the record 48-3 loss they inflicted on their nearest neighbours in January.

The win means Premiership leaders Bristol are guaranteed a top-four place after Northampton lost to Gloucester, while Bath are seventh with their play-off hopes all but gone.

Bristol looked threatening from the off and had an early Malins try chalked off for a forward pass as they coughed up the ball in a number of good positions.

They were somehow two tries down after a two-minute spell as, first, Charles Piutau dropped the ball, allowing Cameron Redpath to kick through to Watson before Priestland - on as a temporary replacement after Orlando Bailey went for a head injury assessment - intercepted a pass from 40 metres out and cantered in under the posts.

Those scores gave Bath confidence - Ben Spencer added a penalty after half an hour to put them 15-0 up and the hosts defended well until Bristol eventually mauled Hughes over from a five-metre lineout four minutes before half-time.

Hughes had a second try ruled out five minutes after the break as a wonderful passing move down the left wing was marred by a knock-on by Luke Morahan before the forward gathered in a cross-field kick.

With Bristol taking control of the game, Bryan Byrne was held up as they continued to pound the home defence - Pat Lam's side earned a penalty try from the resulting scrum as Juan Schoeman was sin-binned.

With an extra man Malins made amends for the first-half try that was disallowed as he ended a great passing move between Charles Piutau and Semi Radradra.

The visitors started to dominate the scrum - prop Kyle Sinckler was excellent just a couple of days after missing out on the Lions tour - and Piutau went in with 18 minutes left with the Bears camped under the Bath posts.

The hosts responded when Watson gathered Priestland's cross-field kick and went over, but any hopes Bath had of rescuing something from the game were over when Tom Dun was sent off for a shoulder into Radradra's head with 10 minutes left.

Earl was forced over from a close-range lineout two minutes later before Malins raced in with the final play of the game.

Bath director of rugby Stuart Hooper told BBC Radio Bristol:

"The scoreboard doesn't lie unfortunately. We played a half where we were pretty decent, put them under pressure, turned the ball over a lot and got our rewards.

"But in the second half we just invited them into the game through indiscipline or field position and they're too good a team to play with 14 men.

"The individual moments of discipline are what they are, they're individual, but as a theme it's too much and you can't legislate for it.

"We've got to be smarter, we've got to be wiser and not make silly decisions on the field that puts the referee in a position when he's only got one option."

Bristol director of rugby Pat Lam told BBC Radio Bristol:

"I think the whole game we had really good control in the sense that we had lots of opportunities.

"We weren't accurate enough, whether it was the line-out to the pass was too flat.

"But we talked about that at half-time, although they were winning we gifted them that, and the opportunities and the game plan was working fine and they came home really strong in that second half.

"I'm so pleased for our supporters because they've taken a lot of pain over the years, but to go four on the trot against Bath now and five in the last six is a massive effort from everyone at the club.

"To get a record score here is also a huge achievement, particularly when you consider we were down 15 points, and to qualify for the semi-finals now, which was our minimum goal, with four games to go is a massive effort too."

Bath: De Glanville; Watson, Clark, Redpath, Muir; Bailey, Spencer; Schoeman, Dunn, Stuart, McNally (capt), Stooke, Bayliss, Reid, Faletau.

Replacements: Du Toit, Bhatti, Judge, Ewels, Ellis, Chudley, Priestland, Gray

Bristol Bears: C Piutau; Morahan, Radradra, S Piutau, Malins; Sheedy, Uren; Thomas, Byrne, Sinckler, Attwood, Vui, Luatua (capt), Earl, Hughes.

Replacements: Kerr, Woolmore, Afoa, Holmes, Heenan, Kessell, Lloyd, Leiua.

Referee: Luke Pearce