1. Sterling stars as leaders enjoy straightforward win

Raheem Sterling scored after just 39 seconds against Watford to extend his hot streak in front of goal as Manchester City bounced back from Sunday's goalless draw against Crystal Palace.

Having failed to equal Bayern Munich's European record of 19 successive league wins at Selhurst Park when they were held by Roy Hodgson's team, the Premier League leaders returned to winning ways by cruising to victory at the Etihad Stadium.

Sterling's 14th league goal of the campaign -- a volley from Leroy Sane's cross -- set City on course inside the first minute before Christian Kabasele diverted the fit-again Kevin De Bruyne's cross into his own net on 13 minutes to make it 2-0.

Sergio Aguero's second-half strike secured City's victory, though Pep Guardiola's team could have won by a greater margin as they reopened a 15-point lead over second-placed Manchester United at the top of the table.

While virtually all of Guardiola's players are showing undoubted signs of improvement this season, Sterling's form this term is perhaps the most eye-catching. The England winger has added goals to his game, after working on his finishing and decision-making in the penalty area.

Before Guardiola took charge at City, Sterling's Premier League career numbers showed 24 goals and 16 assists in 126 games. Since, he has 21 and 10 in just 53 appearances.

And with Sane also upping his game, City's threat on the flanks is a key factor in their dominance of the title race.

Goalkeeper Ederson has also made a huge difference following his summer arrival from Benfica, but the Brazilian was denied a third successive clean sheet when Andre Gray scored a tap-in for Watford on 82 minutes.

2. Key men return but Aguero remains key

David Silva and John Stones were back in action after recent lay-offs, hammering home the strength of City's squad, but the sight of Sergio Aguero scoring again will have been the most uplifting moment of the night for the league leaders.

By his own high standards, Aguero has been off the pace in recent weeks, scoring just three league goals during December. The Argentine international has looked short of his usual sharpness and uncharacteristically missed some straightforward chances against Watford.

With Gabriel Jesus facing up to two months on the sidelines with a medial ligament injury, Guardiola and City need Aguero firing on all cylinders, despite the goal threat offered by Sterling, De Bruyne and Sane.

If City choose not to pursue Arsenal's Alexis Sanchez this month, or fail to land the Chilean forward, Aguero will be their only proven striker until Jesus returns, so he needs to be the Aguero that has become one of the top scorers in Premier League history.

Guardiola has given him tough love at times and Aguero has found it difficult to deal with that, having been City's leading light for so long. But his second-half strike against Watford, which made it 3-0, banished any threat of a barren spell and ensured Aguero will face Liverpool next week with a goal in his most recent league game.

Silva and Stones will also benefit from the action in this game, with the two men shrugging off the ring-rust from their recent spells out of the team.

3. Has Silva missed his moment?

For a while following Ronald Koeman's sacking as Everton manager in October, Marco Silva found himself as the hottest property in Premier League management.

The Goodison Park outfit spent a month attempting to prise him from Watford, but the Vicarage Road hierarchy would not allow their man to speak to Everton and Silva himself refused to force the issue.

So he stayed in situ, having only arrived from Hull six months earlier, but the team's run of form since Silva was linked with Everton has been awful and suggests that both the manager and his players were distracted by the speculation.

This loss at City was Watford's ninth in 13 games since Koeman's dismissal triggered the links between Silva and Everton and that is a worrying run for any manager.

Having fought so hard to keep him during the autumn, will the Watford board be quite so resolute in their determination to stand by the former Olympiakos coach if results continue to go wrong?

Silva has plenty of admirers within the game, but the old maxim of cashing in when you are hot may now haunt the Watford boss. If his team continue to struggle and slide down the Premier League, he may regret not pushing for the chance to speak to Everton.

And Everton, having done well in 10 games since hiring Sam Allardyce, may feel they have had a lucky escape.