|County Championship Division One, Chesterfield|
|Close, day two: Yorkshire 617-5 v Derbyshire 94-5|
|Derbys 0pts, Yorks 6pts|
Alex Lees' unbeaten 275 led Yorkshire to declare on 617-5 before Derbyshire struggled to 94-5 at the close.
Resuming on 171, Lees' maiden double ton came alongside skipper Andrew Gale (74), before Gary Ballance (66) batted with his usual aggressive swagger.
In reply, Chesney Hughes went early and a brief rebuild ended with Wayne Madsen and Wes Durston falling in consecutive Steven Patterson balls to make it 52-3.
Dan Redfern and Ben Slater fell before stumps leaving the hosts in the mire.
After a dominant day one performance, Lees made sure Yorkshire tightened their already vice-like grip on the game by racing past 200 with less than 45 minutes played.
Gale and Ballance both batted positively in support - 92 of their combined 140 coming in boundaries.
Once Gale ended Derbyshire's torment, the hosts' batsmen never got going.
Ryan Sidebottom dismissed Hughes lbw, before Patterson missed out on a hat-trick after he had Madsen caught behind and trapped Durston plum in front.
The home side tried to limp to the close, but Redfern and then Slater nicked Jack Brooks behind on what was a truly awful day for Derbyshire at the County Ground.