Worcestershire were on the receiving end of a century from veteran Durham skipper Paul Collingwood as conditions became more favourable for batting on the third day of the LV = County Championship clash at New Road.
The home bowlers stuck gamely to their task but, after the sun came out, the ball stopped moving around in the manner of the opening two and a half days.
Durham, who were set a target of 318, closed on 270-3 with Collingwood unbeaten on 111 from 167 balls on his 39th birthday with one six and 16 fours.
The game has been a topsy turvy affair with both sides having periods when they were on top.
Worcestershire recovered from 160-5 to a challenging 323 in their first innings after being put into bat in testing conditions.
They looked to be in a position of considerable strength early in the afternoon session on the second day with Durham 103-9 in reply to their 323 all out and in danger of being asked to follow on.
But centurion Scott Borthwick and Graham Onions added 95 for the final wicket and then Durham reduced Worcestershire to 65-6 last night.
Again the momentum switched thanks to some explosive hitting by Joe Leach who again has made telling contributions with bat and ball during the game.
But the cloud cover of the previous two and a half days disappeared when Durham launched their reply.
Leach produced some explosive hitting during the morning session and raced to his half century off only 33 balls with three sixes and 10 fours.
He was eventually last out for 76 as Worcestershire totalled 192 all out.
Leach received good support from Ben Cox (32) and Sachithra Senanayake (18) as the last four wickets added 127 runs.
He had some early good fortune when he edged Chris Rushworth and John Hastings for boundaries and was dropped by Keaton Jennings off Rushworth on the deep square boundary.
But in between he and Cox produced a display of ferocious hitting and the first five overs of the day yielded 53 runs.
Boundaries flowed at a rapid rate from both players against the opening Durham pair with Leach straight driving Rushworth for six.
Leach and Cox added 75 in 9.1 overs before the latter was caught behind by Michael Richardson off Hastings. His 31 ball knock contained five fours.
Senanayake hit a breezy 18 before he fell to a good catch by Mark Stoneman at Long off to give Hastings his fifth wicket.
Shantry (0) departed to the Richardson-Hastings combination but Leach continued to hit out and another 25 were added in partnership with Charlie Morris.
He was finally bowled for 76 from 53 balls with three sixes and 10 fours after making room to cut against Hastings.
Hastings finished with career best figures of 7-60 from 12.3 overs.
Durham were left four overs batting before lunch and reached 20-0.
Stoneman adopted an aggressive approach in racing to 37 out of 53 with a succession of boundaries off Charlie Morris.
He survived one head high chance to first slip off Shantry on 30 but perished when Ben Cox took a fine catch away to his left off Leach.
Borthwick was trapped on the crease lbw to Shantry for four with the total 66-2.
But new batsman Collingwood looked in good touch from the start and he lofted spinner Senanayake for six over extra cover.
Jennings reached his half century off 91 balls with six boundaries and Collingwood went to fifty from 58 balls with one six and seven fours.
Morris broke the stand after tea after it had realised 108 in 29 overs when Jennings pushed forward and nicked through to Cox at 174-3.
Collingwood found another willing partner in Michael Richardson as the former England T20 skipper went to the 31st 100 of his career with a glance for four off Shantry.