Manchester City have been heavily linked with a move for Juventus forward Cristiano Ronaldo.
If Ronaldo does move to the Etihad Stadium he will become the latest player to represent both City and neighbours Manchester United.
Here, the PA news agency takes a look at some of the other names who have worn both blue and red in Manchester.
Denis LawDenis Law enjoyed his most prolific seasons at Manchester United (PA Archive)A prolific striker, Law started his career at Huddersfield before joining City in 1959, spending two seasons with the club and then moving on to Torino.
After just a year in Italy he would sign for United and go on to score 237 goals in 404 appearances for the Red Devils, winning two league titles, the FA Cup and the European Cup.
A return to City would follow in 1973, where he famously scored a back-heel against United on the final day of the season as they were relegated to Division Two.
Brian KiddBrian Kidd not only played for both clubs but also worked as assistant manager for City and United (Barrington Coombs/PA)Kidd came through the ranks at United before breaking into the first-team in 1967, scoring plenty of goals before he left for Arsenal seven years later.
He would return to the north-west when City came calling in 1976, spending three years with the club and averaging almost a goal every other game in league football.
Later in his career, Kidd worked as an assistant to Sir Alex Ferguson at Old Trafford before again making the City switch and working under Roberto Mancini, winning the Premier League in both roles.
Peter SchmeichelPeter Schmeichel enjoyed a fine career at Manchester United (Owen Humphreys/PA)Joining Manchester United as an unknown quantity in 1991, Schmeichel would go to to become one of the best goalkeepers in the club’s history.
He played 398 games for the club, winning five Premier League titles, three FA Cups and the Champions League in his final game for United.
Short stints at Sporting Lisbon and Aston Villa followed before he spent the final year of his career at City, celebrating wildly as they beat his former club at Maine Road.
Andy ColeAndy Cole had a brief spell at Manchester City towards the end of his career. (David Davies/PA)Like Schmeichel, Cole would win the treble at United in 1999 having initially joined the club from Newcastle four years earlier.
A serial winner at Old Trafford, Cole departed for Blackburn and spent three seasons at Ewood Park before a year at Fulham.
He would then head to City, making 22 Premier League appearances in his solitary campaign in blue.
Carlos TevezCarlos Tevez joined Manchester United from West Ham. (Nick Potts/PA)The Argentina international scored at Old Trafford on the last day of the 2006/07 season to keep West Ham in the Premier League before then moving north.
Tevez would enjoy two fine years under Ferguson at United, playing in a frontline with Ronaldo and Wayne Rooney and winning two league titles and the Champions League.
He would make a controversial switch to City as the club proclaimed “Welcome to Manchester” – Tevez captained the club to FA Cup glory in 2011 and won another league title the following season.
Owen HargreavesOwen Hargreaves ended his career with a stint at Manchester City (Dave Thompson/PA)The England international played alongside Tevez as United won the Premier League and Champions League double in 2007/08 following his switch from Bayern Munich.
Injuries would then ruin the rest of him time at Old Trafford as Hargreaves made just four league appearances over the next three seasons.
A surprise free transfer to City in 2011 failed to revive his career despite scoring on his debut and he would retire having played just four times for the club.