As we reach the half-way point of the first round of County Championship Division One matches, a result is already close at Durham, whereas Surrey have work to do against Nottinghamshire and rain continues to affect the state of play at the Ageas Bowl.
Jennings' second hundred leaves writing on the wall for Somerset
It was a case of different season, same result for Somerset as after resuming on 30-3 they collapsed to a miserable 179 all out as Chris Rushworth and Graham Onions took seven wickets between them, the latter returning 4-62.
For Somerset, James Hildreth showed some early resistance before being caught for 27. Lewis Gregory also made 27 as Peter Trego top-scored with 45 from just 57 balls and was the last man out.
Keaton Jennings then had his way once again with the Somerset bowlers, reaching his second century of the match just before the close and finished on 105*, with Paul Collingwood 39* after his first innings duck.
Jennings becomes only the third Durham batsman to achieve the feat of two centuries in a match, the last being Paul Collingwood, who the 23-year-old was batting with when he brought up his second ton of the game.
Elsewhere for Durham Mark Stoneman made 41 as the hosts finished on 223-4 and will start day four with a 300-run lead.
Notts force follow-on at Trent Bridge to leave Surrey in trouble
Australian Jackson Bird was the pick of the bowlers as he took 4-56 to help Notts bowl Surrey out for just 225 at Trent Bridge, Ben Foakes top-scoring for the visitors with a gritty 38, accompanied by 35 from Tom Curran and 32 from Kumar Sangakkara.
Surrey were put into bat once again by Chris Read and finished 14 without loss on day three, 207 runs behind.
Tuesday washout spoils Warwickshire's first-day dominance
There was no play at the Ageas Bowl where Hampshire will resume 189-8 on Tuesday morning after Keith Barker took five early wickets on day one.