Rising Canadian star Milos Raonic, one of the finest servers in tennis, is being tipped as a dangerous outsider for the French Open which begins in Paris on Sunday.
The Montenegro-born, 23-year-old had former world number one Novak Djokovic rattled during last weekend's semifinals at the Rome Masters and despite going down in three hotly-disputed sets, the Serb admitted he struggled badly with the unpredictable Raonic serve.
"I can't recall the last time when I was feeling so helpless returning, even his second serves," said the six-time Grand Slam winner after he battled to a 6-7, 7-6, 6-3 victory before overpowering Rafael Nadal in the final.
Former Canadian Davis Cup player and coach Robert Bettauer believes the cool, composed and confident world number nine may yet go on become one of the best servers of all time.
"His serve gives every indication of being arguably the best in history because of the quality of both his first and second serves when factoring in the consistency of its power, placement, spin, variety and the trajectory coming from a 6ft 5in (1.96m) individual," Bettauer said.
"The proof will be in how that is demonstrated in his career and his results but he is a supremely confident server.
"He is now going toe-to-toe with the top guys and took Nadal to three sets last year at Florida as well as (Roger) Federer twice last season," added the 58-year-old Vancouver native who coached Canada's Davis Cup team in 1987-88 before leading the North Americans at the 1988 and 1992 Olympics.
"He is really knocking on the door of the top five now and I think he is even a better clay court player than on grass because his serve is more effective," added Bettauer, who is also a respected tennis commentator in Canada and runs the Pacific Institute for Sport Excellence in Victoria, BC.
"People talk about the (Pete) Sampras serve but the difference with Raonic is his second ball which has deadly placement, power, spin and variety.
Canadian veteran Daniel Nestor, who has won every doubles' Grand Slam as well as the Olympic gold medal, remarked when watching Raonic as an 18-year-old at a Davis Cup meet in Calgary: "He's going to be a massive player.
Along with Nestor and the fast improving Vasek Pospisil, Raonic led Canada to the semifinals of the Davis Cup last year, taking the scalps of Italy and Spain along the way before finally falling against Djokovic and Serbia in the final four.
"That experience was very confidence building but he has other parts of his game now than just the serve. I think he's a very dangerous threat (at the French Open) and it's not beyond the realms of possibility that he can win," continued Bettauer.
Raonic, who grew up in Ontario but now resides in Monte Carlo, will be seeded eighth in Paris with Argentine Juan Del Potro injured, and his chances look more than good of getting into the later stages and making life difficult for the top seeds.
A Canadian man has never won a Grand Slam singles' title but the rise of Raonic and his much-feared serve will put concern into any player in the field heading to the French capital.