Pakistan captain Younus Khan is looking to inject some positive momentum when the final Test against Sri Lanka begins in Colombo.

Less than a month after being crowned World Twenty20 champions, Pakistan's bewildering defeats in the first two Tests against Sri Lanka - which helped the home side take an unassailable 2-0 lead in the three-match series - have only seen them regress.

A Pakistan side full of potential have degenerated quickly into a petty, squabbling bunch.

Charges of disunity in the team were floated immediately after the team's collapse in the first Test in Galle.

Those accusations gained traction when Younus hit out at his under-performing middle-order following defeat inside three days in the second Test at the P Sara Oval.

It has left the visiting team with a mountain to climb.

Pakistan's defeats have been marked by astonishing batting collapses, all of which has helped Sri Lanka secure their first series victory over their opponents at home.

Younus admitted his team was playing way below potential.

"The team is only about 20% away from being where I want it to be," Younus said.

"For short periods we play great cricket, but then let ourselves down by showing a lack of application.

"Once again it comes down to the lack of Test cricket we have played over the last two years.

"We will be playing for pride and want to get some momentum going into the one-dayers."

The Test series precedes a five-match one-day series.

Coach Intikhab Alam has rubbished allegations of infighting in the team and has called for a leap of faith among the current squad.

"It is nothing new in Pakistan cricket, but I can only urge our former players not to do things which will damage their own team," Alam said.

"The batting has let us down badly, but we can't afford another failure.

"No player wants to fail. I think our senior players are just going through a bad time and need support."

Pakistan's woes have masked an ordinary performance from the home side's batsmen and former skipper Mahela Jayawardene was mindful of the fact.

"To take a 2-0 lead is really pleasing," Jayawardene said.

"But the fact is we are not playing brilliant Test cricket right now and there is some way for us to go to get to our best."

Vaas is back

With the seasoned Chaminda Vaas being included in the squad, Sri Lanka have a potential selection headache ahead of the Test.

Vaas, who only a fortnight ago denied chief selector Asantha de Mel's claims that he had intended quitting the Test arena, was a surprise inclusion in the team for the final Test.

While captain Kumar Sangakkara believes the 35-year-old has a lot to give, local media reports have indicated Vaas was included only to give the paceman an opportunity to make one final bow.

Vaas's inclusion in the final XI is likely to be at the expense of spinner Ajantha Mendis, who has looked ragged in the series.