Shahzad and Sidebottom put Yorkshire in control
Worcestershire 168 and 82 for 4 v Yorkshire 367
Yorkshire took command of their County Championship clash with Worcestershire after Ajmal Shahzad and Ryan Sidebottom put on 109 together for the 10th wicket - Yorkshire's seventh-highest last-wicket stand in the competition.
The pair rushed Yorkshire on to 367 to give them a first-innings lead of 199 and Worcestershire had crumbled to 82 for 4 by the close of the second day, still trailing by 117.
England reject Shahzad led the assault with a fiercely struck 70 off 72 balls, with seven fours and four sixes, before being caught at long on by Alan Richardson off Saeed Ajmal, leaving Sidebottom unbeaten on a more subdued 28 from 84 deliveries with four boundaries.
It was only the 11th Championship century stand for Yorkshire's last wicket and watching the game at North Marine Road was Ryan's father, Arnie, who featured with Arthur Robinson in what was then the second-highest of 144 against Glamorgan at Cardiff in 1977.
But Arnie actually missed his son's big partnership because no sooner had he come in to bat than Arnie temporarily left the ground to take Ryan's two children to the railway station.
"I didn't think he would last too long against the new ball," grinned Arnie. "When I returned to the ground Worcestershire were just about the start their second innings."
Arnie said he still had happy memories of the day in Cardiff 34 years ago when he and Robinson came within five runs of beating the record for the 10th wicket of 148 between Lord Hawke and David Hunter in 1898, a stand later overtaken by one run by Geoff Boycott and Graham Stevenson.
"I can remember taking a single off Tom Cartwright to complete my only first-class century and I did not know at the time what a great bowler he was."
Until Sidebottom the younger joined Shahzad, Yorkshire had failed to take a tight stranglehold on their fellow Division One strugglers and at 258 for 9 they were only 90 runs ahead.
But Shahzad wasted no time in going on the rampage. He got off the mark by striking Jack Shantry over long on for six and in the same over he steered him to the boundary to take the lead into three figures.
Sidebottom's fluent off-drive against Shantry was one of the best shots of the day but it was Shahzad who continued to do most of the damage, and one of two sixes in an over from Ajmal landed on the roof of the stand at the Trafalgar Square end.
He dashed to his half-century off 50 balls with six fours and three sixes before driving Gareth Andrew into the crowd to earn Yorkshire an unexpected fourth batting bonus point, and he took a quick single to raise the century partnership. Just when it was beginning to look as if the pair might set a new record for the county, Shahzad was out attempting one big hit too many.
Yorkshire had begun the day on 135 for 5 but skipper Andrew Gale could only add four to his overnight 68 before he was lbw to Richardson, having already been dropped in the slips in the paceman's first over.
Careful batting by Gary Ballance and Tim Bresnan saw Yorkshire through the morning session without further loss and they had added 92 in 30 overs when Bresnan fell for 41 to the third ball of the afternoon from Andrew, which he played into his stumps. Ballance was lbw to Richardson for a solid 51 off 132 balls, with four fours, and Adil Rashid was similarly dismissed by Shantry to bring the last-wicket pair together.
Sidebottom was soon involved in the action again as his sixth ball of the Worcestershire reply was guided into the slips by Matt Pardoe, and the visitors hit more trouble after Daryl Mitchell and Vikram Solanki had put on 45 together.
Solanki was lbw during a fiery spell from Shahzad and Moeen Ali pushed Rich Pyrah into the covers and was run out by Anthony McGrath's direct hit as he tried in vain to get off the mark. Mitchell, struck painfully on the right thumb by Shahzad, survived until the close when he had reached 38, but late in the day he lost Alexei Kervezee who edged Pyrah to keeper Jonny Bairstow.