Their leading scorer netted all four of Pompey’s goals in a 4-1 triumph to climb out of the Championship relegation zone.
It was the first time since Yakubu in May 2004 that a Blues player has achieved that remarkable feat, arriving against Middlesbrough in the final match of the 2003-04 campaign.
Having fallen behind after three minutes, Colby Bishop set up Lang for his first, before he took advantage of Jay Dasilva’s mistake to make it 2-1 before half time.
Then, after the break, he headed home Freddie Potts’ left-wing corner, before wrapping it up from close range after Bradley Collins had brilliantly saved from Colby Bishop.
A return to winning ways in style for the Blues after the Derby debacle – and here are our player ratings...
1. Nicolas Schmid - 9
Proving an excellent summer signing. When Pompey really needed him, he stopped a one-on-one from Bassette with the Blues already 1-0 down and later came off his line to save at a Coventry man’s feet inside the box. Barely tested in the first half. Photo: Jason Brown
2. Zak Swanson - 8
Recalled to the side and Swanson again showed he’s a player who can be relied on. Strong in the tackle, mobile and uses the ball well. Quite a battle in the right-back spot now. Photo: Jason Brown
3. Marlon Pack - 9
Given yet another central defensive partner, but put in an excellent showing, particularly in the first half. Always has time on the ball and looking ever-comfortable in his new role. Photo: Jason Brown
4. Ryley Towler - 8
Hadn’t made an appearance since August and waited patiently for his chance, then McIntyre’s concerning form prompted Mousinho to turn to him in the centre of defence. Grew into the game, but played the offside trap very well in the first half. Photo: Jason Brown/ProSportsImages