An eye-catching innings against South Africa, who were due to include fast bowlers Dale Steyn, Morne Morkel and Makhaya Ntini in today's team, could only have helped Shah in his bid to add to two Test caps.
Middlesex team-mate Andrew Strauss, meanwhile, asked to face the tourists at Uxbridge, hoping to get a good look at Steyn and Co before opening for England at Lord's next week.
As for South Africa, captain Graeme Smith was declared fit for the three-day game after recovering from a hamstring injury which, initially, looked as though it might keep him out of the First Test.
All-rounder Jacques Kallis, struck on the elbow when playing against Somerset last weekend, also made today's XI.
With Smith back at the top of the innings and Steyn replacing Andre Nel from the Somerset game, the tourists have named a side which, barring injuries, is likely to be picked at Lord's.
While Shah's next match will be Middlesex's Twenty20 Cup quarter-final against Lancashire on Tuesday, Key and Bopara are facing Friends Provident Trophy semi-finals for Kent and Essex respectively.
Key's Kent are at Chester-le-Street today, taking on holders Durham and attempting to reach their first Lord's final for 11 years.
Essex's meeting with Yorkshire at Chelmsford tomorrow presents an opportunity to bury the painful memories of last season's Trophy exit.
Bopara ended up missing the semi-final in Durham because of a thigh strain, then saw his team-mates crumble to 71 all out before mounting a miraculous though ultimately unsuccessful recovery.
Essex had Durham 38 for seven before spinner Danish Kaneria dropped a catch which enabled the eventual trophy winners to edge home by three wickets.
This year, Bopara almost single-handedly propelled Essex into the last four with an astonishing innings of 201 not out against Leicestershire.
The 23-year-old lit up last month's quarter-final with 10 sixes, and his fourth 50 came from just 16 balls.
Tomorrow, however, Bopara will come up against a Yorkshire team led by Darren Gough, who spent three seasons with Essex and is due to retire at the end of the summer.