When Ali Khan burst onto the USA scene out of anonymity in late 2015, his future was filled with immense promise, going from zero to CPL-player in nine months and taking Kumar Sangakkara's wicket with the very first ball he bowled for Guyana Amazon Warriors. But the last two years have been spent in and out of action due to a series of nagging leg injuries, which makes his performance in the recent Global T20 Canada all the more impressive.

While Steven Smith and David Warner grabbed most of the pre-tournament headlines at the Global T20 Canada for making a "comeback" of sorts, Khan was also on the comeback trail. The USA fast bowler from Ohio lost his CPL contract with Amazon Warriors earlier in the year, and was no longer a regular in the USA XI either in part due to his inability to stay on the field.

So it was all the more remarkable for Khan to make a splash at the Global T20, spearheading the Winnipeg Hawks new-ball attack to finish with 10 wickets in eight games, second for the team behind Fidel Edwards. His ability to swing the new ball at 135-140 kph and bowl consistent yorkers that were clocked as high as 145 kph made him one of Hawks' surprise stars of the tournament under captain Dwayne Bravo and head coach Waqar Younis. On Monday, Khan was rewarded with a new contract at Trinbago Knight Riders for the upcoming CPL, called into their squad as a like-for-like replacement for the injured fast bowler Ronsford Beaton.

"Bravo and Waqar Younis, working with them, that has helped me a lot," Khan told ESPNcricinfo. "They gave me a lot of confidence from day one, saying, 'You are the leader of the attack.' I was very confident when I was on the field and they were always supporting me, no matter if I go for runs or don't get wickets or anything. They were always supporting me so I think that helped me a lot to get through all the games."

"Waqar helped me a lot especially with reverse swing and the yorkers. He told me the skills: how to reverse, where to reverse and when to reverse. He always says the best ball in cricket is still a yorker."
Ali Khan

Nicknamed "Yorker Machine" by his USA team-mates, Khan's ability to bowl toe-crushers on demand at a regional tryout held in Indianapolis in September 2015 earned him a spot in a combined North American Associate squad in the following January's CWI Super50. His performances there garnered the CPL contract with Amazon Warriors where he nabbed Sangakkara on debut.

But the two years after his memorable debut wicket for the Amazon Warriors were largely forgettable. Not long after his first CPL season wrapped up, he suffered a major injury to his left hamstring during an innocuous drill - players were being timed while running a three between the wickets - at a USA training camp in Indianapolis in September 2016. A player who prides himself on hustle and effort, Khan stretched himself too far trying to complete the third run to beat the clock ahead of USA's fastest timed player, Timroy Allen. The result was almost 24 months of lingering leg problems.

Khan was so desperate to play for USA, and the USA coaching staff equally desperate to get him in the line-up, that he made his USA debut while semi-fit against Oman in WCL Division Four in Los Angeles a month later. The result was an inspired display in which he bowled Oman's most dangerous batsman, Zeeshan Maqsood, in the first over of the match to set up an eight-wicket romp, a result that went a long way towards ensuring USA won the tournament and gained promotion to Division Three.

But Khan never really gained proper rest and recovery time. USA's players were touring for the Regional Super50 again two months later, and Khan was desperate to keep himself in with a chance of maintaining his standing with Amazon Warriors. More over-exertion resulted in missing the majority of the Super50, resting on the bench with his dodgy hamstring. He maintained his spot with Guyana, but playing for USA he continued to look less than 100% and was eventually dropped midway through WCL Division Three last year in Uganda.

At a USA regional trial this past May in Chicago, Khan seemed 100% fit for the first time in a while, but after taking a wicket and leaping in the air to celebrate, he clutched his right leg on the landing and then limped away. Some of the USA coaches and selectors present let out a gasp and buried their faces in their hands. At times it has been hard to tell which of his two legs is the healthier one.

The fact that Khan took the field in game one for the Hawks in the Global T20 Canada may not have been a miracle. But the fact that he lasted eight games without injury may have seemed like one. Moreover, he never looked tired and instead looked more invigorated as the tournament went on, his speeds continuing to climb as he became less inhibited by thoughts of a possible injury recurrence.

"It's all good now," Khan said. "I'm not injury-scared anymore because I've worked hard when I wasn't playing. When I was injured, I did proper rehab and I am back to full strength now so I don't think about injuries. Hopefully nothing happens in the future but at this point I am feeling as fit as I have ever been."

That return to full fitness allowed him to fully focus on continuing to develop his skills. While he has long been known as USA's best yorker and death bowler, one new weapon unveiled in his arsenal during the Global T20 Canada was an impressive slower ball. He foxed Andre Fletcher and Luke Ronchi, one of the most in-form T20 batsmen worldwide, with his slower ball off back-to-back deliveries against the Edmonton Royals, inducing a pair of skied chances only to see his infielders spill them in the 30-yard circle. He said it's a delivery he has been working on improving for awhile, but that the process was accelerated by working with Waqar.

"Even before the [June USA squad] Texas camp, I was trying to work on a few different things especially my slower ball because my slower ball wasn't as effective as it is now," Khan said. "So I was already working on it with my yorkers but after getting here in the camp, Waqar helped me a lot especially with reverse swing and the yorkers. Working with him in the nets was pretty helpful.

"He told me the skills: how to reverse, where to reverse and when to reverse. He always says the best ball in cricket is still a yorker and not many bowlers can bowl that. So if you can go out there and bowl yorkers the way you do, that's the best ball in cricket. After Bravo left, then David Warner was the captain and he also gave me a lot of confidence, so all of these guys helped me to go out there and perform."

Before Khan rose to prominence to make his CPL and USA debuts, his full-time job was working as a mobile phone sales rep for Cricket Wireless, a national mobile phone network, out of one of their branches in Dayton, Ohio. Now working at a branch in Cincinnati, Khan's back-to-back opportunities with the Global T20 Canada and CPL have forced him to put Cricket phones on hold and given him legitimate aspirations of possibly earning enough money in T20 franchise leagues to make it a full-time career. More pro opportunities for him and other USA players will also help USA's chances of making the next World T20 when regional qualifying begins in September, in addition to climbing up from WCL Division Three on the 50-over rankings ladder.

"First of all I'd like to say thanks to the Global T20 Canada for organising such a tournament where players like us from Associate countries can come up and showcase our skills and talent," Khan said. "It was really hard being on the bench for two years in Guyana. I was definitely learning from the coaches but of course I wanted to play. It was a great opportunity here playing for the Winnipeg Hawks.

"I think it will definitely open doors if I keep performing, but you have to take it game by game. I'm not looking too far ahead. I'm just looking to perform, go out there and do good if I get an opportunity [at Trinbago]. I just want to help my team in any way if I make it into the XI and just leave the rest up to God. I believe everything happens for a reason."

Peter Della Penna is ESPNcricinfo's USA correspondent @PeterDellaPenna