Glamorgan completed a spectacular turnaround of fortunes at New Road as Jacques Rudolph (111) and Chris Cooke (93) added a record 168 for the seventh wicket against Worcestershire, coming together in the depths of 56-6.
After they were both dismissed in one over from Leach, Andrew Salter (80*) and Lukas Carey (54) took up the charge as both hit hard for career-best scores in a stand of 124.
"The way Rudolph and Cooke played was tremendous, it was a great starting point for us to go on for the rest of the day," said Salter, "momentum ran our way so we could get a lead.
"It was nice to share some success with Lukas, he made it look easy towards the end of his innings and he was smoking it- I'm really happy to get a personal best and I'm hoping a hundred's not too far away.
"We're in a great position, hopefully we can take some early wickets and put some pressure on them. The wicket was tricky all day and you never felt in, if you hit good enough areas there's enough there for seam and spin."