The 34-year-old Australian Test spearhead is playing his way back after a seven-month lay-off because of ankle problems.
McGrath had figures of 6-56 off 32.3 overs and 4-30 off 18 overs in NSW second XI's nine-wicket win over Victoria in Melbourne last week.
McGrath admits he wants to prove he's in good enough form to be ushered into the current Sri Lankan Test tour if one of the fast bowlers breaks down.
"I'm bowling better than even before the last Ashes series," said McGrath, whose last Test was against Bangladesh in Cairns last July.
"The game I played in Melbourne last week was the best I've felt for years," he said on Wednesday. "I'm just trying to keep myself as fit and strong as possible."
McGrath, ruled out of Steve Waugh's farewell Test against India in January because of his ankle problems, said he was "so happy" to have returned in time for the last game at the Sydney Cricket Ground for Steve and Mark Waugh against Queensland.
NSW and Queensland can make the Sheffield Shield final against Victoria in Melbourne it if they win outright this week, but they also need Tasmania to be denied points by Victoria in Hobart.
McGrath named in NSW squad