Cristiano Ronaldo's transformation into one of the most prolific strikers the game has ever seen seemingly began following a red card he received at Portsmouth's Fratton Park back in 2007.
That's according to a forthcoming book entitled: 'Messi v Ronaldo: One Rivalry, Two GOATs, and the Era That Remade the World's Game', which charts the rise to superstardom of the two eternal rivals.
Ronaldo - then in his first stint at Manchester United - clashed with Pompey's former Scottish international midfielder Richard Hughes in the closing stages of a 1-1 draw in August 2007.
During their scuffle, the Portuguese superstar appeared to lean in with his head towards Hughes.
The Portsmouth man proceeded to make the most of the perceived contact, something that likely persuaded referee Steve Bennett to give Ronaldo his marching orders.
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It was a harsh call - and one that left United boss Sir Alex Ferguson absolutely fuming. However, the decision was made and Ronaldo was forced to sit out the Red Devils' next three Premier games against Manchester City, Tottenham and Sunderland.
An international break in between the Tottenham and Sunderland fixtures would mean that Ronaldo wouldn't represent United in a competitive fixture for more than a month.
Not required to travel with the first team or take part in the vast majority of training sessions, Ronaldo was essentially a free man over the period of his ban.
Given the supposed harsh nature of the red card, many players might have decided to spend the month feeling sorry for themselves.
Not Ronaldo, though.
PORTSMOUTH, UNITED KINGDOM - AUGUST 15: Cristiano Ronaldo of Manchester United grimaces as Referee Steve Bennett points to the sideline, after showing him the red card for his involvement in a goalmouth fraca during the Barclays Premier League match between Portsmouth and Manchester United at Fratton Park on August 15, 2007 in Portsmouth, England. (Photo by Mike Hewitt/Getty Images)
Rather than seeing out his suspension with his feet up, the player who had made his name as a fleet-footed winger up until that time, decided he wanted to use his unexpected spell on the sidelines to add to his already impressive game.
The crazy training regimen that helped turn Ronaldo into one of the most feared goalscorers in the world
Ronaldo sought out the assistance of club coach Rene Meulensteen to help him evolve as a player during his enforced sabbatical.
Early in this process, per the Daily Mail, Meulensteen offered the theory that Ronaldo was "more concerned with the quality of the goals he scored, as opposed to the quantity."
In order to change the player's mentality towards goalscoring, the Dutch coach tasked Ronaldo with studying video of club legends such as Eric Cantona and Ruud van Nistelrooy, encouraging him to analyse what made them so prolific in front of goal.
MANCHESTER, UNITED KINGDOM - OCTOBER 06: Cristiano Ronaldo of Manchester United scores against Wigan Athletic and point to his cut on his eye while celabrating during the Barclays Premier League match between Manchester United and Wigan Athletic at Old Trafford on October 06, 2007 in Manchester, England. (Photo by Phil Cole/Getty Images)
Once Ronaldo had poured over hours of footage, the pair headed out to the training pitch where Meulensteen devised a series of training drills designed to hone the star's instincts.
An extract from the book explains: "Meulensteen set up drills to make Ronaldo aware of his positioning on the field and show him how to score from different angles inside the box.
"He devised a map of the pitch and goal to categorise every type of finish. Focusing on three distinct locations - directly in front of goal (zone 1), either side (zone 2), and out wide (zone 3) and nine different areas of the goal."
Meulensteen's methods were a hit with Ronaldo who apparently couldn't get enough of the training sessions. The coach would even find the player waiting for him outside his office when he arrived for work.
SEOUL, SOUTH KOREA - JULY 19: England's Manchester United player Cristiano Ronaldo participates in a training session at SangAm World Cup Stadium on July 19, 2007 in Seoul, South Korea. Manchester United will play against South Korea's Seoul FC on July 20. (Photo by Chung Sung-Jun/Getty Images)
While being interviewed for the book, Meulensteen estimated that Ronaldo took at least 5,000 shots at goal during their month working together.
He said of the period: "Ronaldo's whole mindset towards finishing changed.
"It went from ‘I want to score the goal of the season’ to 'I want to be a goal machine.' He was on a mission!"
How much did Ronaldo improve in front of goal after his suspension?
Up until his red card v Portsmouth, Ronaldo had hit 50 goals in 196 games during his time at United (per the Daily Mail) - averaging just one goal every 3.9 games.
From when he returned from his ban until he departed the club for Real Madrid in 2009, he smashed 68 goals in just 96 outings - representing a return of one goal every 1.4 games.
Garnacho WONDERGOAL! Real Sociedad 0-1 Man Utd (The Football Terrace)
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Of course, the five-time Ballon d'Or winner went on to eclipse those numbers as he hit his prime.
There's no way of knowing for sure how much of an impact Meulensteen's training sessions had on Ronaldo's ability to find the back on the net with outrageous regularity.
However, without them, there's seemingly a chance that football history could look very different indeed.
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