Skipper Dimuth Karunaratne battled through back pain to extend Sri Lanka's second-innings lead to 323 after key strikes by Pakistan's bowlers in the second test In Galle on Tuesday.
The hosts reached 176-5 when bad light stopped play early on day three, with stumps called in Galle after more than half an hour's wait for conditions to improve.
The left-handed Karunaratne, on 27, and Dhananjaya de Silva, on 30, were batting in an unbeaten stand of 59.
"The wicket is a bit slower than the first couple of days," spinner Ramesh Mendis, who claimed five wickets to help bowl out Pakistan for 231 in the opening session, told reporters.
"We need to bat as deep as possible and get maximum runs possible. This is a good batting wicket."
Ramesh said the hosts would likely be safe with a lead of 400 and believes the captain and coach Chris Silverwood will decide on a possible declaration if they keep batting.
Pakistan's highest chase in Sri Lanka came in 2015 when they made a target of 377 in Pallekele, and the tourists chased down a Galle record of 342 in the series opener.
Sri Lanka were in trouble at 117-5 when Karunaratne, who stayed off the field during Pakistan's innings, and De Silva got down to the grind.
De Silva took on the opposition bowlers and hit six boundaries with Karunaratne happy to play anchor. The skipper got help from the physio in between his knock.
Karunaratne rotated the strike and also hit two boundaries including a reverse sweep for four off legspinner Yasir Shah.
MATHEWS DISAPPOINTED
Pakistan had earlier rattled the Sri Lankan batting with key wickets including Angelo Mathews in his 100th test after the former captain, who made 35, attempted to rebuild the innings with Dinesh Chandimal.
Offspinner Agha Salman got Mathews out for his maiden test wicket after Pakistan reviewed the umpire's call, with ultra-edge technology confirming a spike when the ball passed the bat and into the hands of slip.
Mathews walked back shaking his head after failing to capitalise on another good start in his landmark test, after he made 42 in the first innings.
The in-form Chandimal, with scores of 206 not out, 76, 94 not out and 80 in his last four innings, looked good on 21 but fell caught behind off fast bowler Naseem Shah soon after tea.
Naseem, who took three wickets in Sri Lanka's first innings, had struck first with the wicket of Niroshan Dickwella, who fell for 15 after opening in place of the ailing Karunaratne.
"They have a lead of about 320 and we will try to restrict them and get a target of around 350-360," said Naseem.
"Bowl them out soon tomorrow and stay positive in the chase. It doesn't look that it will turn big on day four and five, but you never know."
Pakistan's innings ended after the tourists resumed the day on 191-7, in reply to Sri Lanka's first innings of 378.
Offspinner Ramesh sent back Nauman Ali and then trapped overnight batsman Yasir lbw for 26 to record a third five-wicket haul in his 10th test to wrap up the innings.
Pakistan lead the two-match series 1-0 and Sri Lanka are looking to draw level on a pitch which has favoured the batsmen so far.
SRI LANKA:Dimuth Karunaratne (capt), Oshada Fernando, Kusal Mendis, Angelo Mathews, Dinesh Chandimal, Dhananjaya de Silva, Niroshan Dickwella (wkt), Ramesh Mendis, Prabath Jayasuriya, Dunith Wellalage, Asitha Fernando
PAKISTAN:Abdullah Shafique, Imam-ul-Haq, Babar Azam (capt), Mohammad Rizwan (wkt), Fawad Alam, Agha Salman, Mohammad Nawaz, Yasir Shah, Hasan Ali, Nauman Ali, Naseem Shah