Worcestershire skipper Daryl Mitchell won the toss and elected to bat on the opening day of the LV = County Championship match with Yorkshire at New Road.
SriLankan spinner Sachithra Senanayake was included for his county debut after arriving in this country yesterday morning.
There was also a Championship debut for batsman Alex Gidman after his move from Gloucestershire on a two year contract.
Moeen Ali was part of the Worcestershire side in his first competitive match since suffering a side strain while on World Cup duty with England.
Worcestershire: Mitchell, Oliver, Moeen Ali, Fell, Gidman, Kohler-Cadmore, Cox, Andrew, Senanayake, Shantry, Morris.
Ryan Sidebottom took the new ball and Mitchell got off the mark from the final ball of his first over with a single to fine leg.
Jack Brooks made the first breakthrough for Yorkshire when Richard Oliver (0) was caught behind by keeper Andrew Hodd.
Moeen Ali came to the wicket to rapturous applause and got off the mark when he edged Sidebottom between wcket-keeper and first slip for four,
The England all-rounder then flicked Sidebottom off his legs for two.
Brooks claimed a second wicket when Mitchell (4) fended a delivery to Jack Leaning at second slip with Worcestershire 11-2 in the eighth over.