Ronnie O'Sullivan may play on for several years and beat Stephen Hendry's record of seven world snooker titles, says his friend Jimmy White.
Four-time champion O'Sullivan, 37, ended a break from the game announced in November to say he would return in April to defend his title.
"With Ronnie's talent and fitness he can play for a good five years. I think he can beat Hendry's record by winning more than seven titles," White, 50, told BBC Sport.
O'Sullivan said: "Always in the back of my mind, I was never ready to retire. That was never my intention."
After playing one competitive match in the 2012-13 season, the Essex player - nicknamed "The Rocket" - announced a sabbatical until the end of the season, citing personal issues away from the table.
While many will welcome the return of snooker's most high-profile player, who has suffered with depression previously, others feel he has too much of the limelight.
White believes the attention is merited, likening his impact to that of record-breaking Barcelona forward Lionel Messi in football.
"Snooker needs him - Ronnie brings the Messi factor. He's got so much natural talent, people just enjoy watching him. The main reason people love him is his style of play," said "Whirlwind" White.
O'Sullivan plans to write the story of his life, which saw him make his televised debut aged 14 but was overshadowed three years later as his father was jailed for murder following a nightclub fight. Ronnie O'Sullivan Sr was released in 2010.
The player also has three children of his own from two previous relationships and has reportedly been dating Holby City actress Laila Rouass.
"I'm writing a book which will cover what has happened over the last few years and the reasons I did pull out of snooker. The full story will be in there and everyone will be able to read between the lines," he said.
Once the formalities of completing his World Championship entry by Thursday's deadline are concluded, O'Sullivan will begin playing again in practice matches.
"I think he starts on Monday which will give him six weeks before he actually plays, he'll be in as good as shape as ever, if not better," said White.
"What people forget is last year he didn't play in many tournaments and nor did Ali Carter, because there are so many on the circuit, and he got to the final."
While O'Sullivan has slipped to 24 in the provisional world rankings, he is top seed as reigning world champion.
He is scheduled to return at 10:00 GMT on Saturday, 20 April to face a qualifier from outside the top 16. If he progresses to the second round, he will face the 16th seed, or that player's winning opponent.
White, who needs to win three qualifiers to make the televised opening round, realises a clash with O'Sullivan would be a snooker romantic's dream coupling, but believes rivals will be fearful of his friend.
"Listen, let's be honest, who wants to draw him in the World Championship? I want to qualify and I don't want to play him," he said.
O'Sullivan has won snooker's biggest prize in 2001, 2004, 2008 and 2012. Last year, he was the oldest victor since 45-year-old Ray Reardon in 1978.
Despite a lack of match practice, Hendry has previously claimed O'Sullivan would only need a fortnight to prepare, but White said he plans to start practising in earnest next week.
"This year I've stopped working the clubs and I want to get to the World Championship and I'm going to practice with him," said White, who was runner-up six times in the 1980s and 1990s.
"He needs to work on nothing. He's one of those gifted players. I still make 147s [maximum breaks] but keeping it together for two weeks is harder for me."
O'Sullivan conceded his comeback had not been guaranteed.
"If I had other work and things to do I probably wouldn't have come back to playing, but I was sitting around and didn't really have much of an aim," he said.
"I had a little practice and enjoyed hitting a few balls. The rankings system has changed so I don't have to enter every tournament. In my heart I thought I could come back, hopefully still compete and do myself some justice.
"Maybe I need to come back for my own routine, if you like. I don't get as excited about winning tournaments as everyone else around me.
"I have as much fun in a snooker room with no-one watching as I do playing in the final of the Crucible or on telly. I'm oblivious of what's going on around me when I'm playing.
"The break was something I needed to take to get myself out of a situation I felt that I was in, that I had no control over, which would then have meant I couldn't have given snooker 100%.
"The pressures of the game are enough without having pressures outside of the game as well. It wasn't a decision I made easily but I knew it wasn't a decision had to make."
World Snooker spokesman Ivan Hirschowitz denied the sport suffered in O'Sullivan's absence.
"We've been amazed this season our ticket sales have gone better than last season and our viewing figures are up as well," he said.
"I think it shows that although Ronnie is arguably the biggest draw worldwide, the game is bigger. There are more great players, there is more of a buzz about the game."