The 28-year-old's career stalled after he became mandatory challenger to then-WBC super-middleweight champion Badou Jack in 2016 but watched from the outside as Jack instead fought James DeGale before vacating his title.
Smith responded by entering the first World Boxing Super Series (WBSS) and progressing to the competition's final in Jeddah, where he will instead challenge WBA champion Groves and when he believes he has his greatest chance of succeeding.
Jack has since continued to impress, including at light-heavyweight, but while Smith believes he would have beaten him, he is similarly confident he has improved in the last two years and that Groves' route to the WBSS final has come at a cost.
The champion, 30, stopped Jamie Cox before outclassing Chris Eubank Jnr until the final round in which he dislocated his shoulder and put his career in jeopardy.
He insists that the screws since inserted into it and his injury rehabilitation means he has fully recovered, but Smith, whose victories over Erik Skoglund and Nieky Holzken were more routine, said: "From the outset people said I had a tougher route to the final.
"Looking at it, he probably did. I had a tougher quarter-final, but he had a tougher semi-final. If I could go again I would pick my one because he's had a tougher route in terms of physical fights.
"He had a very hard fight in the semi-final though he won comfortably. He put miles on the clock (with that injury). He's had a great career and I can't knock him for that. He's achieved what I want to achieve. But in doing that it's come at a cost: miles on the clock.
"I am a better fighter than I was (when I expected to fight Jack). I haven't had any bad injuries. I haven't been out of the gym."
A rivalry persists between Smith's trainer Joe Gallagher and Shane McGuigan, who works with Groves, but Gallagher attempted to play it down when he said: "We had a pay-per-view situation. We had (McGuigan's) Carl Frampton, a nice kid. (My fighter) Scott Quigg, a nice kid. Someone's got to be the baddie so I was the d***head.
"Shane has matured and he understands what it's like to run a big stable now. The respect's there.
"(What) he's done is get George Groves back to what he was very good at doing with (former trainer) Adam Booth. He's not turned a Ricky Hatton to a Sugar Ray Leonard. He's just reminded George of what he's good at. That's it.
"Ask me about Josh Taylor, then yeah he's done a fantastic job with Josh
"(Groves is) a very hard man. Jaw bashed, (injured) shoulder, knocked out at Wembley, down on the canvas in Las Vegas. He's a man. At that time I wouldn't
say Callum Smith was a man, but he is now. He's 28, he's got a man's