Pep Guardiola always springs a tactical surprise in big matches and Manchester United know that more than most.

Guardiola underlined his status as a top-class manager back in May 2009, when his Barcelona side defeated Manchester United in the Champions League final thanks, in part, to a tactic involving the positioning of Samuel Eto'o and Lionel Messi. Eto'o, who had played the majority of the season upfront, started wide-right. Messi, who had occupied the right-sided role, started in the centre. Eto'o opened the scoring from the right and Messi sealed the victory from the centre. It wasn't an entirely new approach, but it wasn't quite what Manchester United had been expecting, either.

On Sunday, for Manchester City's 2-1 victory over United at Old Trafford, Guardiola did something very similar. From the teamsheets, it seemed the surprise was simply that Gabriel Jesus was starting instead of Sergio Aguero and, even then, it wasn't a huge surprise considering that Aguero had only managed two goals in his past five matches, both from the penalty spot. Through the first five minutes it appeared to be a straight swap: Jesus up front, Raheem Sterling wide-right, Leroy Sane wide-left. Then, however, things changed.

This has been another hallmark of Guardiola's approach in big matches: he starts with one shape but then his side switch to a different formation a few minutes into the game in an attempt to confuse the opposition managers and players. He once masterminded a victory over Jose Mourinho's Real Madrid at the Bernabeu with an approach that started with a four-man defence and then switched to a three-man defence after a few minutes.

Sunday's change was more subtle but no less significant. Having played on the left all season, Sane switched to the right flank. Jesus, the notional centre-forward, went left and Sterling, City's outstanding attacker this season, went centrally and played as a false nine. This was a huge moment to see Sterling deployed in the Messi role.

Literal comparisons with Messi should be avoided for now, but this was Guardiola's most blatant attempt yet to play "The Barcelona Way," or at least His Barcelona Way: a false nine dropping deep to link play, bringing the centre-backs up the pitch, allowing two centre-forwards starting from wide positions to cut inside and finish with their stronger foot. City never quite perfected one of those attacking moves -- United's defending in open play was largely good -- but Sterling was, subtly, very effective in that false nine role.

Raheem Sterling's reinvention in a central, false-nine role is significant to Man City's success this season. OLI SCARFF/AFP/Getty Images

Sterling has often been portrayed as somewhat ignorant in the British tabloid press, but throughout his career he's consistently demonstrated great tactical intelligence.

In Liverpool's nearly title-winning campaign of 2013-14, Sterling generally started on the flank but was sometimes used as a No.10 at the top of a diamond by Brendan Rodgers, such was his ability to find space and link play. That summer, England manager Roy Hodgson decided -- having witnessed Wayne Rooney's ability to mark Andrea Pirlo two years beforehand -- that Sterling had the tactical intelligence to be handed that central role. Sterling was then often used at wing-back by Liverpool the next season, rarely neglecting his defensive duties.

Against Man United on Sunday, Sterling played the false nine role effectively. He was always coming towards play while checking over his shoulder to assess the positions of Marcos Rojo or Chris Smalling, who were dragged out of position towards him. He often played a simple backwards pass before attempting to exploit that space himself, a classic Messi trait. Sterling wasn't afraid to drop into conventional midfield positions in front of Ander Herrera and Nemanja Matic, helping to overload United in midfield and allowing City to dominate that zone. Matic clumsily fouled him in the early stages, unable to cope with Sterling's quick feet.

Those quick feet, and short stride length, make him very difficult to dispossess in tight situations on the edge of the box, and a couple of Sterling's brighter moments nearly created goals. He poked a clever through-ball to Jesus, who peculiarly decided to back-heel the ball rather than taking on a shot. Sterling then played a one-two with Jesus and then couldn't quite squeeze in a shot under pressure from Rojo. He also had a shot blocked after Fernandinho drifted the ball onto his chest.

Sterling was always threatening and while City's goals arrived from set-pieces rather than from open play, City had earned those opportunities by virtue of their constant pressure.

Things changed after half-time: Guardiola made a strange decision to introduce Ilkay Gundogan for Vincent Kompany, with Fernandinho going into defence, and it unsettled City. The subsequent correction, with Eliaquim Mangala replacing Jesus, altered City's plans in the final third. Many were surprised to see David Silva go upfront but it largely made sense. City hadn't been playing with a conventional striker but a false nine, and Silva has played that role before. With no Jesus, Sterling reverted to his old position as a winger but it was no slight upon his performance in that central role.

Using Sterling centrally wasn't a decisive tactical move from Guardiola: the goals arrived from set-plays, and it's barely received any attention in the British press among talk of the post-match food fight. But in a brand new role, Sterling attempted the most shots and the most dribbles for City, created the joint-most chances and his pass completion rate was behind only Kompany and Fabian Delph, players in considerably deeper positions, where they're under less pressure.

Sterling's rise has been arguably the main story of City's incredible start to the campaign and this leap of faith from Guardiola -- dropping City's all-time record goalscorer to accommodate Sterling centrally -- demonstrates how much his manager believes in him. With his intelligence, trickery and new-found penchant for poacher's goals, Sterling's future might be as a centre-forward.