James Rew and Kasey Aldridge both went ages as Somerset played a dead-end draw with Lancashire on the final day in Manchester.
Somerset batted all day, extending their second set to 398-5 before hands were shaken.
Lancashire were without injured England paceman James Anderson for a third consecutive day.
After dispatching 14 overs to take it 2-16 on day one, England’s top wicket-taker did not feature in the game again – and Lancashire head coach Glen Chapple has said he will was apparently a groin injury.
It was Anderson, 40,’s last game for Lancashire before the single Test against Ireland at Lord’s on June 1, followed by the start of the Ashes series against Australia at Edgbaston on June 16.
When asked if Anderson needed a CT scan, Chapple told BBC Radio Lancashire: “It’s up to England to sort it out. It looks like a twisted groin to me.
“He played very well the first innings, but he just irritated his groin. I don’t think it’s too serious.
“We should be positive about his recovery, but he’s done it badly enough to not be in the game again.”
Rew, this season’s top scorer in the Championship, added to his budding reputation by scoring an unbeaten 118, his second game century and the 19-year-old’s third of the season.
He shared an unbroken 192-point stand with Aldridge, whose first-class first century on 101 ultimately ended the game.
Starting at 114-3, Somerset lost Tom Kohler-Cadmore when he played inside a delivery from Will Williams that knocked his stump off.
Tom Lammonby then went for the best 78 of the season before being stumped trying to launch Tom Hartley towards the new hotel under construction mid-wicket.
But, with the lead now over 300 and no statements forthcoming, the only question remained was when Rew and Aldridge hit triple digits.
While this year’s T20 Blast is set to start next weekend, Lancashire will sit out the County Championship for a month until they host Hampshire at Southport on June 11.
Somerset, also still winless after five matches, still have a game four days before the start of T20 – at Lord’s against Middlesex, from Thursday.