I know in Oleg Maskaevs first fight he Ko’d Mirschnechenko who was 21-0 and I believe a former Olympian. What are some others ?
Michael Carbajal fought Will Grigsby who ended up winning two world titles. Only impressive in retrospect though, obviously. If your going to count losing efforts too, then it would be Pete Rademacher no contest. I don't think you can get a tougher pro debut.
I don't know if this counts, but Holyfield had an epic fight in his pro debut in light heavy. It's not like Holyfield did a fine performance or anything but it was an entertaining fight tbh....
BHOP but for a very different reason. He lost his first pro fight after a long prison Stent. The fight took place at 175 and from what I have read, he wasn't in the best of shape. Instead of becoming discouraged and doing something stupid and going back to prison, he dedicated himself to being the best fighter that he could be and dropped down to 160 to become one of the greatest that ever lived. He grinded his way to the title that hard way.
First off, great shout by @George Crowcroft on Roberto Duran-Carlos Mendoza, who later challenged Wilfredo Gomez very competitively for the 122-pound title. This Bhop fight reminded me that James Scott, himself out of learning to box in prison, ventured to Miami to turn pro and draw 8-0 with 6 KOs John L Johnson, who didn’t amount to much but that’s a pretty steep debut. Scott won a 6-round decision. EDIT: James ‘Bonecrusher’ Smith was stopped by a body shot from James Broad in his pro debut. Broad had been a member of the 1980 U.S. Olympic team (the U.S. boycotted those Moscow Olympics) and KO’d Marvis Frazier in one in the finals at the Trials. Next up, Bonecrusher beat Rickey Parker, 2-0 at the time but would later be a cruiserweight champ.
Besides those already mentioned, several other world champs debuted against a future champion: Freddie Castillo lost against Guty Espadas Miguel Vazquez lost against Canelo Alvarez Thongchai Utaida lost against Chana Porpaoin Magne Havnaa won against Johnny Nelson
Of course, you wouldn't know it at the time to call it a great debut, but future welterweight champ Curtis Cokes won a 6 round decision over future 2 time welterweight challenger Manny Gonzalez (one of the times was against Cokes). It was impressive because Cokes never fought an amateur fight. Gonzalez had had a few pro fights already and I believe Manny had an impressive amateur career too, but not sure on that one. Something nagging in my head that he was an AAU champ but not sure.
Riddick Bowe went in against a potential banana skin in Lionel Butler. Lionel could bang. Six years on he was Lennox Lewis' comeback opponent after the McCall loss. Mind you, as I looked on Boxrec to check my memory, I noticed Lionel's debut was against Phil Jackson who went on to fight for the title. Wish today's fighters' managers would show a fraction of that belief in their charges.
One very impressive pro debut win just caught my eye. In 1998 Hideyasu Ishihara made his pro debut against Nolito Cabato. Cabato was a Phillipino journeyman, who moved his career to Japan in 1994, with 22-17-3. He was undefeated since, in 15 contests and while defending his Japanese title, He beat the likes of Kazuhiro Ryuko, Celes Kobayashi and Masamori Tokuyama. He also scored a draw with Kobayashi and Tokuyama each, two future world champions. That's when He met Ishihara and was beaten over 6 rounds. I'm now very curious of how this match-up came about. Was it suppose to be a tune-up for Cabato? Or did They have that big hopes for Ishihara?
Floyd Mayweather Jr. had well-rounded defense and offense, as well as beautiful combinations in his debut.