Melbourne Stars coaching staff had to tell Haris Rauf to stop bowling in the nets during the lead-in to his unlikely debut and they look set to do the same for the KFC BBL final rematch on Saturday.

Rauf is the houseguest who never left, yet the Stars have extended their welcome for the rest of the season as he grabbed 3-25 to fire the Melbourne Stars to the top of the BBL standings heading into their showdown with bitter rivals Melbourne Renegades at the MCG.

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Plucked out of Hobart club cricket, the former salesman and IT student from Rawalpindi with just one Pakistan Super League (PSL) season under his belt is the competition's third leading wicket taker with 10 scalps at the alarming average of 7.10.

That's despite playing just three games, two as a fill-in for his idol Dale Steyn and the other on Thursday in Sydney's west for the injured Sandeep Lamichhane, of a possible five.

The weekend's derby will be Steyn's final game for the season with young English quick Pat Brown already secured as his replacement and while Lamichhane missed the Thunder clash with a thigh strain, he is expected to return on Saturday and be available for the remainder of the summer.

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But Brown's selection for England's ODI and T20 squads to face South Africa means he will miss the BBL finals, paving the way for Rauf to return should the Stars make the top five as excepted.

The Stars' final regular-season game is on January 25, with the BBL finals beginning January 30. BBL clubs are permitted to play only two international players per game but can have up to six on their roster during the season.

"I never even knew Haris was here until I got here," Steyn told cricket.com.au.

"I didn't know much about him and watched him bowl in the nets before the first game he played and he scared everybody.

"He was bouncing guys and eventually they had to go to him and say, 'look, you've got to stop bowling now. We've got a game tomorrow. You can't injure any of these guys.'"

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Rauf went on to return tidy figures of 2-20 off four overs in his debut against the Brisbane Heat, before devastating the Hobart Hurricanes with a five-wicket haul and donating the match ball to a security guard he met before the game.

It comes after he only won a spot on PSL side Lahore Qalandars' list after impressing at an open trial where he caught the eye by bowling at speeds approaching 150kph.

Nick Larkin, player-of-the-match for his breakthrough 45-ball 65 on a slow Showgrounds pitch against the Thunder, admitted: "Not too many guys like facing him.

"He's pretty sharp and he doesn't mind sending them in around your thigh and your ribs.

"He's a passionate guy … he's excited when he's taking wickets and I think he's really grateful to be playing in the BBL."

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Perhaps the most exciting element for the Stars is that Rauf still has improvements to make, with Steyn explaining Rauf's inexperience has meant he requires increased guidance on occasion.

Maxwell was visibly frustrated at times during Rauf's spell on Thursday as the Thunder scrapped to a competitive total, taking him aside for an animated chat after his initial two-over burst.

They were later exchanging hugs and grins after he clean bowled Daniel Sams and top-scorer Alex Ross (the latter with a delivery that clocked at 147kph) in the space of three deliveries.

The pair had another discussion as players left the field after the 26-year-old quick conceded 10 runs from the final over of the innings.

"He hasn't played a lot of cricket at this level," said Steyn. "It's important for him to have somebody that's there – I'm sure he's never played against a lot of these players.

"It's important for him to stand there and talk to him, and explain, 'this guy might lap (sweep), or this guy might give himself some room.'

"At the same time, Haris needs to execute the skills that he's good at. I think he did that nicely today.

"Bowling the 20th over is always tough, teams want to finish with some quick runs. It was another learning curve for him, but I thought he bowled beautifully."

Added Larkin: "Maxi's pretty clear with his plans and communicates quite extensively with the bowlers throughout.

"It's not uncommon to see him go up and say, 'hey, what happened there? That wasn't part of a plan,' or 'excellent, that's great – do you want to change the field?'

"He's taken 10 wickets in three games, so he's performing like a seasoned pro."