The opening duo made little impression in the drawn first Test at Lord's and were both dismissed for four in the first innings of this match.
But, on the final day of three, their stand of 118, with Butt scoring 84 and Farhat 64, took Pakistan most of the way to their victory target of 160.
Former Pakistan captain Rashid Latif has been among those calling for the hard-hitting Shahid Afridi to once again open the innings.
And with vice-captain Younis Khan, fit again after a knee injury which saw him miss the opening match of a four-Test series, making 58 in the first innings of this tour game, one of either Butt or Farhat could be omitted at Old Trafford if Faisal Iqbal is retained after his second innings 48 at Lord's.
Butt's runs came from 120 balls with 15 fours while Farhat's knock featured two sixes and six fours.
Pakistan's pace bowling reserves remain depleted with Shoaib Akhtar, Rana Naved-ul-Hasan and Mohammad Asif, all missing at Lord's, also out of the second Test of the series.
Mohammad Sami and Umar Gul were Pakistan's new-ball duo at the 'home of cricket' but they face competition for their places from Shahid Nazir, who took three for 33 in Northamptonshire's second innings, as well as uncapped seamer Samiullah Khan Niazi.
England, who saw star all-rounder Andrew Flintoff ruled out for 12 weeks on Saturday, are due to name their second Test squad Sunday.