Daryl Mitchell and Tom Fell have both scored 14 runs each in the match in the first innings.
The hosts won the toss and invited the visitors to take guard.
Pakistan declared their first innings at 261/3 with skipper Azhar Ali being the top scorer with 81 runs off 140 balls with 10 boundaries and a six to his name.
Shan Masood made 67 runs from 149 balls after hitting six fours in the match.
Mohammad Rizwan and Iftikhar Ahmed remained unbeaten at 49 and 41 runs respectively.
Ed Barnard, Alex Hepburn and Alexei Kervezee took a wicket each for Worcestershire.