A brutal display of power hitting by Islamabad United opener Luke Ronchi helped his side defeat Karachi Kings by eight wickets at the Dubai International Stadium on Sunday and qualify for the Pakistan Super League 2018 final.

The kiwi batsman scored the fastest half-century of PSL on his way to an unbeaten 39-ball 94 to move his team to within one victory of their second title triumph in three years.

Both the sides were without their regular captains, with Islamabad's Misbahul Haq nursing a hand injury and Karachi's Imad Wasim recuperating from concussion.

After the Kings won the toss and opted to bat first, United's Samit Patel and Mohammad Sami — both of who were rested for their defeat at the hands of Karachi in the final league match of PSL 2018 — returned to share the new ball.

Their impact was instant as the start to Karachi's innings was rocky. Sami, in particular, was excellent early on, removing both Khurram Manzoor and Babar Azam in the fourth over.

His catch of Manzoor off his own bowling was a superb effort and a testament of the 37-year-old pacer's fitness.

Sami gave away just seven runs in his opening two-over spell.

With the supremely in-from Azam gone, the pressure was on the English pairing of Joe Denly and Eoin Morgan to rebuilt the Karachi innings.

With their score just 21-2 at the end of 5 overs, theirs was a doubly difficult task of not only stabilising the ship but also accelerate the run flow.

But their partnership didn't last long, with Morgan, in the 9th over, planting an easy catch into the hands of United's stand-in skipper JP Duminy.

Halfway through their innings, Karachi were 52-3 and in need of some major fireworks in their remaining 10 overs.

Both Colin Ingram and Denly agreed, hitting a boundary each in the 11th and showing their intent.

However, runs dried up again following that 11th over, with the next boundary not coming until the 15th over — at the end of which Karachi were 96-3 and going at pedestrian pace in a T20 match.

The only edge they had was that Ingram and Denly were both set batsmen and perfectly placed to accelerate in the final five overs.

Part-timer Hussain Talat had bowled a decent 13th over, on the basis of which he was given the 16th over as well. But this time Ingram treated him with two 6s, which was just what Karachi needed at the time.

Denly completed his half-century in the 18th over, hitting a straight 6 to Faheem Ashraf. But unfortunately, he was out hit wicket the very next ball as Karachi's hopes of conjuring up a 160 plus total were dented.

Sami bowled a decent 17th before Ingram, on the final ball of the 18th, hit an excellent improvised shot to beat the third man fielder, bringing up his 50 in the process.

The express bowler out of Karachi was again extremely difficult to hit in his last and the innings' 19th over, finishing with figures of 20-2.

The usually reliable Ashraf had a rare off day with the ball; his and the innings' final over went for 17 runs as he finished with figures of 53-1.

Ingram's unbeaten 39-ball 68 helped Karachi to a decent, if not spectacular, 154-4.

Both Patel and Sami were excellent with the ball for United. Another player who was not risked for Karachi's win over United on Sunday was the hard-hitting Luke Ronchi.

In his absence, United's top order had suffered a rare bad day — a major reason the Kings made the play-offs.

This time, Ronchi was playing and doing what he does best. The opening over of Mohammad Amir went for 14 and featured three Ronchi boundaries.

In-form Usman Shinwari's second was a quiet one before Ronchi rattled Tymal Mills with a trio of boundaries in the third.

With Amir and Mills' opening overs conceding three boundaries each, the ball was tossed to Shahid Afridi to try his luck. It changed nothing as Ronchi smashed three boundaries in the leggie's first over.

Ronchi hit two consecutive sixes in the 5th over, completing the fastest 50 of PSL history. His record half-century took just 19 balls.

By the end of the 5th over, Islamabad were a staggering 69-0 and had all but ended the encounter.

Karachi bowlers' nightmare start was not helped by three dropped catches — two of which were offered by Ronchi.

With runs flowing and pressure gone, the young Sahibzada Farhan, who had an underwhelming PSL 2018, played a couple pretty looking strokes of his own.

Farhan (29 off 18) departed on the final ball of the 7th over, by which time United were 91-1.

But Ronchi was simply in a class of his own, giving zero respect to anyone who dared hurl the ball at him. He welcomed Mohammad Irfan Jr with three consecutive boundaries.

Halfway through their innings, Islamabad were 124-1 and in need of a paltry 31 runs to qualify for their second PSL final in three years.

Ronchi's rampage and the Kings' suffering wan't over just yet.

His unbeaten 39-ball 94-run innings, which featured 12 boundaries and five maximums, finally came to an end when there were no more runs to chase. Islamabad United reached their target with 8 wickets and 45 balls to spare. Yes, you read that right.

Line-ups

Karachi Kings: Khurram Manzoor, Joe Denly, Babar Azam, Eoin Morgan (capt), Colin Ingram, Shahid Afridi, Mohammad Rizwan (wk), Mohammad Irfan Jnr, Mohammad Amir, Usman Khan, Tymal Mills

Islamabad United: JP Duminy (capt), Alex Hales, Hussain Talat, Luke Ronchi (wk), Asif Ali, Sahibzada Farhan, Samit Patel, Shadab Khan, Faheem Ashraf, Amad Butt, Mohammad Sami