Big Picture
Before the series began, you suspected these were well-matched sides. Both have been blown away in Australia this year. They live in the same neighbourhood on the Test rankings: Sri Lanka sitting sixth, Pakistan at eighth. Both have captains appointed this year, new coaches, and a reputation for failing to develop the blinding talents that enter the team. The Rawalpindi Test - what little of it was played at least - was further indication that there is not much to separate them. Sri Lanka had tough conditions to bat in, but fought their way to a competitive total. Pakistan had good batting conditions, and made ample use of them on the final day.
Where Pakistan can perhaps impose themselves in Karachi is on the bowling front. They have the quicker attack overall, and if the Karachi track turns out to be stereotypically flat, that could amount to a substantial advantage. Yasir Shah may be suffering a crisis of confidence - his average up at over 120 from three overseas Tests this year - but if there is one side he has excelled against through his career, it is Sri Lanka.
Sri Lanka's attack, meanwhile has been doubly depleted. They had fielded an inexperienced pace attack in Rawalpindi, with Suranga Lakmal unavailable for the tour and the selectors unwilling to pick Nuwan Pradeep due to his frequent injuries. With Kasun Rajitha now out of the Karachi Test, an even less experienced bowler is set to slot in. Where in their last two series - in South Africa and Sri Lanka - the attack had bowler-friendly tracks to work with, they may have to work harder for their wickets in Karachi. A major test awaits, not only of the attack itself, but of Dimuth Karunaratne's ability to marshal it.
The visitors, though, have at least won Tests this year. Pakistan last won in November 2018, before losing five consecutive Tests, to New Zealand, South Africa and Australia. It seems unlikely that Sri Lanka will blow Pakistan away in Karachi, but they will at least hope they can scrape together a flawed performance that lurches them haphazardly to victory, which has been their blueprint for victory under Karunaratne.
Form guide
Pakistan DLLLL (last five Tests, most recent first)
Sri Lanka DLWWW
In the spotlight
Some of the buzz before Rawalpindi was how Fawad Alam had finally forced himself into a Test squad after years of domestic achievement, but it was Abid Ali whose long wait for a Test spot coalesced into a vindication of his selection. Abid appeared confident for the majority of his innings, a brief short-ball barrage by Lahiru Kumara the only passage of play in which he appeared even slightly uncomfortable. He's clearly in excellent touch now, and another good outing in Karachi will help keep Imam-ul-Haq (a contender for the opening spot) at bay.
Dilruwan Perera's year has been almost as bad as Yasir Shah's. In four Tests - in Australia, Sri Lanka, and in Rawalpindi - he has only five wickets and averages 89.40 in 2019. What has been especially disappointing about his performance is that in the first year without Rangana Herath, Dilruwan was expected to lead the spin attack. Instead, he has been outperformed even by the likes of Dhananjaya de Silva. The only man in the attack with more than 20 Tests to his name, he needs wickets in Karachi to retain his position as Sri Lanka's senior spinner.
Team news
Usman Shinwari is out of the Test with typhoid. Yasir Shah is likely to enter the XI.
Pakistan (possible): 1 Shan Masood, 2 Abid Ali, 3 Azhar Ali (capt) , 4 Babar Azam, 5 Haris Sohail, 6 Asad Shafiq, 7 Mohammad Rizwan (wk), 8 Yasir Shah, 9 Mohammad Abbas, 10 Naseem Shah, 11 Shaheen Afridi
Sri Lanka may field two spinners, with left-arm spinner Lasith Embuldeniya likeliest to come into the XI in place of Kasun Rajitha.
Sri Lanka (possible): 1 Dimuth Karunaratne (capt), 2 Oshada Fernando, 3 Kusal Mendis, 4 Angelo Mathews, 5 Dinesh Chandimal, 6 Dhananjaya de Silva, 7 Niroshan Dickwella (wk), 8 Dilruwan Perera, 9 Lasith Embuldeniya, 10 Vishwa Fernando, 11 Lahiru Kumara
Pitch and conditions
Unless the Sri Lanka team lives up to its reputation of taking their island's rains with them wherever they travel, there should be more cricket in Karachi than the 167 overs seen in Rawalpindi. Clear skies and temperatures in the mid 20s are forecast for the duration of the match.
The surface in Karachi is reputed to be a batting fantasy, but it is difficult to predict now, with Tests not having been played here for 10 years.
Stats and trivia
Yasir Shah has 40 Test wickets from five Tests against Sri Lanka. His average of 21.65 is his best against any opposition.
Sri Lanka haven't lost a bilateral Test series in Pakistan since 1991. They have won two series here since, in 1995 and 2000.
If Pakistan lose this Test, this will be the first calendar year in which they have gone winless since 1991 (a year in which they only played two Tests).
Dilruwan Perera averages 51.35 away from home, but his average against Pakistan in the UAE was slightly better, sitting at 29.15 after three Tests.