Fakhar Zaman (L) is congratulated by teammate Mohammad Rizwan after scoring fifty in Sharjah on Friday. AP
Rizwan and Fakhar Zaman (53) put on a key stand of 116 after Pakistan lost skipper Babar Azam for nine in a match which will decide the final Super Four berth of the six-nation tournament.
Khushdil hit five sixes including four in the final over to finish with a flourish in his unbeaten 35 off 15 balls as Rizwan watched the blitz from the non-striker's end in a partnership of 64.
The loser of the contest will go out of the tournament, which acts as a tune-up to the T20 World Cup in October-November in Australia.
Fakhar Zaman plays a shot while Hong Kong's wicketkeeper Scott McKechnie watches. AP
Bowlers kept the Pakistan openers under check with a disciplined line and length and spinner Ehsan Khan got the key wicket of skipper Babar Azam for nine in the third over.
Azam hit a boundary off Ehsan's off spin but the bowler soon got revenge with a caught and bowled to silence a largely Pakistan crowd.
The left-handed Fakhar Zaman joined Rizwan, a wicketkeeper-batsman, and the two attempted to rebuild, hitting a few boundaries between them to improve the scoring rate.
Pakistani fans cheer for their team during the T20 match at Sharjah Cricket Stadium on Friday. AP
Spinners Yasim Murtaza and Mohammad Ghazanfar kept the batsmen restricted to singles and twos on a slow and low pitch until Rizwan broke the shackles with a straight six.
Rizwan kept chipping away and got his fifty off 42 balls to raise the bat amid raucous applause form the crowd. Fakhar also changed gears and reached his fifty with a towering six off Murtaza's left-arm spin, but got out next over to Ehsan after his 41-ball stay. Khushdil then tore into the opposition bowling and ended the innings with three successive sixes.
Babar Azam (R) shakes hand with his Hong Kong counterpart Nizakat Khan while they arrive for toss at Sharjah Cricket Stadium. AFP
Earlier, Hong Kong skipper Nizakat Khan won the toss and elected to field first against Pakistan.
"We are very good at chasing. We are going to make sure today that we stick to our plans and execute them," the Pakistan-born Nizakat said at the toss. "Back in Hong Kong, we play on slow, low wickets. This is very similar and we also rely on spin."
Pakistan, led by Babar Azam, lost a close first match to India and will be looking to make the next round with the same team. "We would have batted first," said Azam. "We wanted to put runs on the board and put them under pressure."
Afghanistan, Sri Lanka â€” both from Group B â€” and India (Group A) have already made the Super Four.
Hong Kong: Nizakat Khan (capt), Yasim Murtaza, Babar Hayat, Kinchit Shah, Aizaz Khan, Scott McKechnie (wk), Zeeshan Ali, Haroon Arshad, Ehsan Khan, Ayush Shukla, Mohammad Ghazanfar
Pakistan: Babar Azam (capt), Mohammad Rizwan (wk), Fakhar Zaman, Iftikhar Ahmed, Khushdil Shah, Asif Ali, Shadab Khan, Mohammad Nawaz, Naseem Shah, Haris Rauf, Shahnawaz Dahani
Umpires: Raveendra Wimalasiri (SRI), Ruchira Palliyaguruge (SRI)
TV Umpire: Masudur Rahman (BAN)
Match Referee: Jeff Crowe (NZL)