Chasing a target of 158 runs, Gladiators crossed the finishing line thanks to solid batting performance from opener Shane Watson. The Aussie all-rounder struck six fours and four sixes in his 55-ball 81.
Shane Watson was given a life when was clean bowled off Sami’s bowling but it was declared a no-ball with Sami hitting the stumps at his own end in his delivery stride.
Umar Akmal picked up where he left off with a valuable 28-ball 44.
Samit Patel, Rumman Raees and Cameron Delport claimed a wicket each.
United had given themselves a chance when Ahmed Shehzad was bowled in a rather unusual manner of Patel’s bowling. Rossouw soon followed Shehzad but then it was all about Akmal and Watson who took the game away from the opposition.
Earlier, Islamabad United posted 157-8 in their 20 overs, after Sarfaraz Ahmed won the toss and elected to field first.
Despite losing three wickets for just eight runs, the two-time PSL champions recovered superbly.
All-rounder Wayne Parnell topped the batting charts with 41 off 20 balls, while Asif Ali and Hussain Talat chipped in with 36 and 30 runs respectively to post a competitive total on a slightly slower surface.
All-rounder Sohail Tanvir was the pick of the bowlers, as he returned with figures of 4 for 21.
Leg-spinner Fawad Ahmed claimed three wickets for 15 runs.
Gladiators, who now sit on top of the table, will face Multan Sultans in their next encounter. Islamabad United will face Peshawar Zalmi on February 22.