Somerset reached tea on 134/8 on the third day of their LV= County Championship match against Nottinghamshire at Trent Bridge, an overall lead of 220.
Batting for a second time, after dismissing the home side earlier in the day for 226, Somerset ran into difficulties losing half their side for only 45.
Marcus Trescothick was bowled in the first over of the innings by Vernon Philander, completing a pair in the match for only the second time in his career.
Philander also removed Johannes Myburgh in the early exchanges and Luke Wood also picked up two of the wickets to fall.
Jake Ball bowled Jim Allenby and then trapped Peter Trego as the game remained in the balance.
Alex Barrow scored 25 before miscuing against Harry Gurney, allowing Steven Mullaney to take a well-judged catch at midwicket.
When a heavy shower brought an early conclusion to the afternoon session Lewis Gregory was unbeaten on 26, with Craig Overton yet to get off the mark.