Glamorgan all-rounder Graham Wagg says his team are "still on top" against his former side Derbyshire.
The hosts are 122-2 in reply to Glamorgan's 410-9 dec as the Welsh county look for a record fifth consecutive Championship win.
"We've got to work hard in the morning but we could go bang-bang-bang and all of a sudden they could be five down. We're still well in this game."
Wagg led the way 62 off 64 balls with Glamorgan's batsmen all scoring freely.
Colin Ingram made 89, Craig Meschede 70 and David Lloyd 55.
In the home reply, Ruaidhri Smith ran out Derbyshire opener Hamish Rutherford for 36 before trapping Chesney Hughes lbw in his next over.
But captain Jacques Rudolph dropped a slip chance from rival skipper Wayne Madsen just before the close.
"Unfortunately we put down a chance but we played fantastically well to get into this position," said Wagg.
"The weather's played a big part, there's a lot of work to be done but there's a lot still in the wicket. As long as we can control the scoreboard I think the wickets will come."
Wagg is also enjoying a return to the county where he played between 2006 and 2010 before moving to Glamorgan.
Mark Wallace was able to bat and keep wicket despite dislocating his thumb on the opening day of the game.