Teenager Tim Rouse played a starring role as Bath began their bid to win back their Wadworth 6X West of England Premier 1 crown with a resounding 163-run win at Ashcott & Shapwick.
Skipper Robin Lett and his predecessor, Tom Stayt, also started the season in fine form, scoring 115 and taking 5-26 respectively to help sink the newly-promoted hosts.
Lett won the toss and elected to bat first on a very green-looking wicket.
A fiery opening spell from James Hayman (2-39) soon had the visitors in trouble at 24-3, though, before Kingswood schoolboy Rouse walked to the crease.
Making only his third 1st XI appearance, Rouse played beautifully and contributing heavily towards a fourth-wicket stand of 183 with Lett.
He was eventually caught behind off the bowling of James Haggett after making a match-turning 95 from 125 balls.
Useful late contributions from Sam Mount (18) and Tom Stayt (17no) saw last season's runners-up to a strong-looking 277-6 at the halfway stage.
Ashcott's reply was thwarted early by a magical spell from opening bowler Stayt and from 45-6 the game was effectively over.
Reece Croker (2-18) and Lloyd Davies (2-28) wrapped up the match to give Bath a maximum 22 points and the perfect start to their campaign.
Keynsham's first match back in the top flight after six years away ended in a narrow defeat at Bridgwater, the side who pipped Bath to the title last term.
Sam Wheller bagged 4-27 to leave the champions in trouble at 96-6 after they were inserted by visiting skipper Gary Worgan.
Jonathan Vickery (44no) and Andrew Skidmore (55) then put on a decisive 108 for the seventh wicket to help the hosts to 207-7.
Worgan (39) was the only one of Keynsham's top five to reach double figures in reply and they finished 15 runs short of their target on 192-8 despite 60 from Matthew Taylor.
Corsham also opened their summer with a loss, going down by 19 runs at Frocester.
New skipper Robin D'Souza (2-43) and Ashur Morrison (2-41) claimed two wickets each as Corsham Frocester posted 212-7 after being asked to bat first.
Tom Shaw's 34 was Corsham's top score in reply despite nine of their batsmen reaching double figures.
