While the opener Grant ground his way to a resolute, undefeated 88, his brother Andy, the captain, powered to his second Test century as Zimbabwe reached 289 for 3 by the close.
Andy Flower's unbeaten 142 came from 215 balls and included one six and 18 fours, while Grant batted the full six hours and hit one six and four fours in his 289-ball innings.
It was easily the highest partnership for the still-fledgling Test nation, beating the 194 for any wicket by Alistair Campbell and Dave Houghton against Sri Lanka at the end of last year.
It also left them just 17 runs short of the 264-run world record for a Test partnership between two brothers, set by Greg and Ian Chappell against New Zealand in Wellington in 1973-74.
Such a total looked unlikely as the Pakistan seam attack of Wasim Akram and Aqib Javed removed Mark Dekker, Alistair Campbell and Dave Houghton with only 42 on the board.Reuse content