Pakistan’s shocking defeat in first Test vs Sri Lanka

After outplaying Sri Lanka for the first three days, Pakistan cricket team was surprisingly all out on the fourth day when it lost their last eight batsmen for 46 runs, giving the visitors a dramatic 50-run victory in the first cricket Test at the Galle International Stadium. Chasing a modest target of 168, Pakistan were collapsed from a seemingly impregnable 71-2 to 117 all out in their second innings before lunch on the fourth day. Pakistan’s astonishing defeat gave Sri Lanka a 1-0 lead in the three-Test series, the first between the two nations since gunmen attacked the Sri Lankan team bus in the Pakistani city of Lahore on March 3. A stunned Pakistan captain Younis Khan said the team's lack of Test cricket -- just three Tests in the last 18 months -- had proved costly. The team who a few days ago emerged as the champions of the World Twenty20 Cup could not achieve an easy target despite dominating the game for three successive days. What do you think were the factors behind this defeat?