Anyone who witnessed his duel with Shane Watson during the World Cup quarter-final in Adelaide - blistering pace against an out-of-sorts, but game batsman - will long remember it.
"It's definitely a great weapon for me and I am working hard on it. I try to be consistently hitting 145-150kmph, and if my rhythm is good I can go much higher."
Riaz is relishing the idea of playing alongside fellow left armer Mohammad Amir after his five-year absence and is sure Pakistan have the goods to trouble New Zealand with players such as the canny veteran Umar Gul, here for the T20 leg, and the giant left armer Mohammad Irfan, who pitches up for the ODI matches.
"Definitely Amir is a great addition to the team. He's getting a chance, he's a great fast bowler, he has proved that in the past and it's time for him to prove it again.
"Probably with him here there's less pressure on me as a bowler because getting his support, plus Umar Gul is back so it's going to be a good combination for Pakistani cricket."
As for New Zealand's batsmen, "it seems like cricket is very easy these days for them because they are hitting the ball really well".
Something Riaz and co are aiming to stop.