Somerset 172 (Leach 30, Killeen 5-36) and 71 for 1 need a further 194 runs to beat Durham 277 and 159 (Pretorius 3-46, Henry 3-51)
The Rothesay County Championship match between Durham and Somerset looks set for a absorbing three-day finish after 18 wickets fell on the second day of the game at the Banks Homes Riverside.
Replying to Durham's 277, Somerset mustered only 172 but then dismissed the home side for 159, thus leaving the visitors with a victory target of 265.
When bad light ended play five overs early, they had reached 71 for 1, still 194 short of their target but with nine wickets in hand.
However, the day was also memorable for Durham's 20 -year-old Championship debutant, Mitch Killeen, who had received his county cap on Friday morning and took 5 for 36 in Somerset's first innings.
Somerset resumed on 63 for 3 but Ben Raine took the first wickets of the day when he had James Rew lbw for 8 in the third over of the morning and Jack Leach superbly caught in the gully by Emilio Gay for a 30 that had included six fours.
But the remainder of the morning session belonged to Killeen, who took four wickets in 16 balls as Somerset collapsed to 128 for 9. Tom Abell was lbw to one that nipped back off the pitch for 5 and Andy Umeed was dismissed in similar fashion for 14 when hit on the back leg.
Craig Overton was out to his first delivery when his attempt to work the ball on the leg side merely leading-edged a comfortable catch to Gay in the gully, and Killeen completed his five-wicket haul in his next over when Archie Vaughan pushed forward but only edged a catch to Colin Ackermann at second slip.
There was a reminder of cricket's ability to bring players down to earth when Matt Henry hit Killeen for three fours in his next over and that brief assault was the foretaste of a last-wicket partnership that yielded 44 valuable runs for the visitors. Codi Yusuf ended the fun when he bowled Migael Pretorius for 20, leaving Henry unbeaten on 23 and giving Durham a first-innings lead of 105.
That brought an end to one period of helter-skelter cricket. In less than 90 minutes, Somerset had scored 109 runs and lost seven wickets in 21.4 overs. It also concluded Yusuf's part in the match. After being hit on the helmet on Friday evening, he was diagnosed as suffering from concussion at lunchtime and replaced by Daniel Hogg.
The start of Durham's second innings continued the morning drama as Henry took two wickets in three balls in his second over. Ben McKinney was caught behind and Gay taken by Lewis Gregory at first slip, both for ducks, to leave the home side on 9 for 2, and they had only advanced to 18 for 2 when the luncheon interval gave everyone an opportunity to take a deep breath or two.
Rain delayed the start of the afternoon's play for 20 minutes but the interruption only compounded the batters' problems. David Bedingham was caught at slip by Overton off Josh Davey for 8 and the modest recovery represented by Alex Lees and Ollie Robinson's 31-run stand ended when Lees was lbw to Pretorius for 35 and Ackermann was caught down the leg side off Overton for 4.
Durham's lead was only 193 when Robinson was caught in the gully by Umeed off Pretorius for 35 and Raine could add just nine more runs before he slapped Henry to Abell at cover.
But James Minto joined Clark and this pair batted sensibly to add 26 before Clark was lbw to Pretorius four balls after tea. Minto and Hogg then added 21 for Durham's last wicket before the home side were bowled out for 159, Pretorius taking 3 for 46 and Henry 3 for 51, giving him match figures of 7 for 111.
Despite being faced with a daunting target on a spicy pitch, Gregory and Davey batted sensibly against an inexperienced attack to put on 35 before Killeen knocked out Davey's off stump. That brought Tom Lammonby to the crease and he and Gregory had added a further 36 runs before the gloom closed in.
