Mitchell McClenaghan and Jack Shantry both picked up two wickets before lunch to strengthen Worcestershire's victory hopes in the LV County Championship clash with Gloucestershire at Cheltenham.
McClenaghan again bowled with great pace and aggression and removed nightwatchman Tom Smith and Will Tavare during his opening four over spell.
Then Shantry replaced the New Zealander at the Chapel End and sent back Alex Gidman and Hamish Marshall in successive overs.
By lunch Gloucestershire, who had resumed on 10-1 after losing skipper Michael Klinger yesterday evening, had moved onto 103-5 still needing a further 136 to avoid an innings defeat.
Smith was given a searching examination by McClenaghan before he brought about his downfall.
The spinner edged one delivery just short of third slip and nicked another for four to third man.
But after making nine, he tried to cut McClenaghan and edged through to wicket-keeper Ben Cox.
Skipper Daryl Mitchell employed an ultra attacking field for Alex Gidman consisting of five slips, backward point and a short third man.
McClenaghan struck again when Tavare (11) attempted to pull came and the ball came off the toe end of the end and ballooned high into the air to Charlie Morris backward of square leg.
Morris had bowled a fiery spell at the College Lawn End in tandem with McClenaghan.
McClenaghan was replaced after a spell of 4-0-12-2 by Shantry and the left armer was soon into his stride.
Gidman played some fluent strokes if making 37 but he then played inside the line to Shantry and was bowled to leave Gloucestershire on 79-4 in the 25th over.
That ended a parrtnership of 49 in 12 overs between Gidman and Hamish Marshall.
Shantry continued to probe away and in his next over he accounted for Marshall (15) was deceived by a delivery which swung late and gave Cox his third catch of the innings at 84-5.
