Alex Lees celebrated his new contract with a career-best unbeaten 171 as Yorkshire dominated the opening day of the LV= County Championship match against Derbyshire at Chesterfield.
The 20-year-old from Halifax scored his second Championship hundred in three games and shared a Yorkshire record second-wicket stand against Derbyshire of 311 with Phil Jaques who made 139, his first century of the season.
The title contenders closed on 367 for two which added up to another tough day for the bottom team in Division One although 19-year-old off-spinner Peter Burgoyne impressed on his Championship debut and was unlucky not to take a wicket in his 33 overs.
Yorkshire announced before the start of play that Lees had signed an extended contract until December 2015 and the young left-hander showed why he is so highly regarded with a chanceless hundred after Adam Lyth had been dismissed in the seventh over of another stiflingly hot morning. It was a good day to win the toss but Mark Footitt found some late seam movement to have Lyth caught behind for 10 with the total on 22 but the pitch was an excellent one to bat on and Lees and Jaques took full advantage.
Jaques looked a little anxious at the start of his innings but he became increasingly assured and pulled Mark Turner for six before straight driving the fast bowler for his sixth four to reach 50 from 68 balls.
Lees had brought up his half-century in the previous over when he drove Burgoyne through the covers for his ninth four but the young spinner bowled few loose balls during a spell of 23 overs broken only by lunch from the Lake End that cost only 42 runs.
It was an impressive effort in testing conditions and the Derbyshire attack stuck to their task without really troubling the second-wicket pair who scored 134 runs in the afternoon session.