WATCH: Ronaldo trains with Manchester United for first time in 12 years as he prepares for 'second debut'

Cristiano Ronaldo has returned to training as a Manchester United player for the first time in 12 years after sealing his incredible move from Juventus, going through his paces at a session on Tuesday.

Ronaldo called quits on his time at Juventus despite having one year left on his contract, with United swooping in for the 36-year-old star just as it seemed he might make a move to bitter crosstown rivals Manchester City.

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The Old Trafford club will pay an initial €15 million ($17.7 million) to Juve for the transfer in a deal which could rise to €23 million, while some reports indicate Ronaldo will bag in excess of $500,000 a week across his two-year contract, with the option of a further season on top.

After arriving in the UK from international duty with Portugal – which was truncated when Ronaldo picked up a suspension with a yellow card against Ireland – the star number 7 was seen going through his paces at United’s training ground on Tuesday.

Striding out with midfielder Juan Mata, Ronaldo seemed in good spirits before working with the crop of United players not currently on international duty.

The Portuguese icon – who left United for Real Madrid in 2009 after six years at the club – could make his ‘second debut’ in the Premier League clash with Newcastle at Old Trafford this weekend.

Ronaldo won three Premier League titles and the Champions League during his first spell at the club, scoring 118 times in 292 appearances. He also won the first of his five Ballons d’Or while at the Old Trafford giants.