Yorkshire struck three times at the start of Worcestershire’s second innings to maintain the advantage on day three at New Road, but England star Moeen Ali is a potential danger.
Gary Ballance finished with a brilliant 194 in Yorkshire’s first-innings 428 all out having started the day on 417-9.
He was caught at long-leg having top-edged a pull at Ed Barnard.
Jack Brooks, Ben Coad and Steve Patterson all struck at the start of Worcester’s second innings, which slipped to 63-3 in the 13th over.
They have since reached lunch on 120-3, a lead of 32.
Brooks had Daryl Mitchell caught behind, Coad had Tom Fell caught at second slip and Patterson forced Joe Clarke to play on.
Moeen then played in a particularly free-flowing manner on the way to a 55-ball half-century, including clipping Tim Bresnan’s first ball over long-leg for six.
He will begin the afternoon 65 alongside Alex Milton on 10.
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