Tom Willis' late try helped Wasps start their Premiership campaign with a narrow win over Bristol.
A trio of Jimmy Gopperth penalties edged Wasps ahead after Sam Bedlow had kicked the Bears ahead.
Harry Randall burrowed over for Bristol before Jack Willis' try - given after review - put Wasps back in front.
Bears skipper Siale Piutau crossed to restore the lead in a dramatic final quarter, but Willis touched down with two minutes left to nick the win.
In a repeat of last season's Premiership play-off semi-final, Wasps made it 11 straight Premiership wins against Bristol, and 15 league matches unbeaten against the west country side - a record which stretches back to September 2006.
Bedlow, in his first start at fly-half, earned the Bears a deserved lead after a dominant opening 15 minutes, but after individual errors cost them at two attacking lineouts, Gopperth levelled with Wasps' first possession in Bristol territory.
A forward pass denied Bassett a nailed-on try as the hosts came on strong in an even first half, and despite a disciplined defensive effort, Bristol fell behind when a wayward Randall pass eventually led to a penalty in front of the posts, with Gopperth taking advantage.
Niyi Adeolokun's fine cover tackle denied Zach Kibirige a clear run to the line as the hosts started the second half strongly, and Gopperth's boot duly extended Wasps' lead to 9-3 after Bristol conceded a penalty from their own scrum put-in.
Juan de Jongh was shown a yellow card for offside and Bristol took advantage when Randall's quick tap and spin carried him over the line with the visitors camped on the Wasps line. Bedlow's conversion nudged Bristol ahead.
Bedlow's long-range penalty stretched the lead, but Jack Willis emerged from a mass of bodies to claim a try which a lengthy TMO review confirmed, and Gopperth's conversion gave Wasps a 16-13 lead to spark a topsy-turvy final 10 minutes.
Piutau crashed over from close-range as Bristol looked destined to end their barren run against their bogey side, but the hosts landed the knockout blow as Josh Bassett broke down the wing and gave Tom Willis a run in under the posts with two minutes left.
Wasps director of rugby Lee Blackett:
"If we turn up and play like that we will be beaten most weeks, but with the limited preparation time we knew we would only be playing on 90% efficiency.
"We weren't even able to achieve that figure as it was a far-from-great performance, but we showed great confidence and real character to get over the line.
"There's plenty more to come from us with young players like Tom Willis and Alfie Barbeary making a big impact coming on from the bench."
Bristol director of rugby Pat Lam:
"Our effort, commitment, physicality and defence were all outstanding, and we put a lot of work into our defence as they are a dangerous side.
"You have to play the full 80 minutes against them and not switch off at all, and there were key mistakes in letting them in for the final try.
"Our execution was poor at times, we made silly mistakes in attack by taking the wrong option, but overall it was an excellent effort."
Wasps: Sopoaga; Kibirige, De Jongh, Gopperth, Bassett; Umaga, Vellacott; McIntyre, Taylor, Brookes, Cardall, Gaskell, Willis, Young (c), Shields
Replacements: Cruse, West, Toomaga-Allen, Douglas, Barbeary, Willis, Wolstenholme, Odogwu
Sin-bin: De Jongh (48)
Bristol Bears: O'Conor; Adeolokun, Leiua, S Piutau (c), Purdy; Bedlow, Randall; Thomas, Byrne, Afoa, Holmes, Joyce, Vui, Thomas, Heenan.
Replacements: Capon, Woolmore, Armstrong, Hawkins, Dun, Kessell, Wilstead, Fricker.