1 Can the champions catch Manchester United?

As Manchester City kicked off at Arsenal, United's lead over their city rivals was 10 points, though what had appeared a canter of a victory turned into a far more attritional three points. Liverpool were making a case for not being the best barometer of United's championship credentials when they fell two behind as Sir Alex Ferguson's men strolled through them. But once the visitors scored United suddenly looked like a team that could yet be caught – both in this match and by Roberto Mancini's City come May – and they began this quest by restoring their deficit behind United to seven points by winning at the Emirates Stadium.

2 What did José Mourinho's team learn?

The "hooded one" sat next to Roy Hodgson in the posh seats, covering his head throughout against the cold as he took notes in preparation for United's visit to Real Madrid on 13 February for the first leg of their last-16 Champions League match. Beyond Robin van Persie's clinical finishing the Portuguese will have noted the threat of Shinji Kagawa in the United No10 role: the playmaker's deft touch, ghosting runs to the opposition area and ability to recycle the ball from deep inside his own half carry a threat that requires neutralising. But Mourinho can also inform his side United are brittle when the contest is taken to them, as the second 45 minutes showed – Real's coach will tell Cristiano Ronaldo to collect the ball and run directly at Rafael da Silva and Patrice Evra, who were both vulnerable on Sunday afternoon.

3 Liverpool can be heartened by second half

Brendan Rodgers' side were close to awful before the break. Steven Gerrard was mugged by Van Persie. Joe Allen under-hit a backpass to Pepe Reina that should have been punished by Danny Welbeck to score United's second. And Gerrard was again the culprit with a heavy pass in an attempted one-two with Luis Suárez when the latter closed in on goal. These were just three illustrations of a too tentative Liverpool side during the opening 45 minutes. When United scored their second the sense was they might take a hammering. Instead after Daniel Sturridge's goal United became the nervy ones and were grateful for the final whistle.

4 Robin van Persie bests Luis Suárez

The showdown of the star strikers after the first half ended with Rodgers deciding that his No7 required help. On came Sturridge to link up with the Uruguay forward, who dropped in behind the former Chelsea man. Before this Suárez had been becalmed, as Van Persie continued to do what he has done all season. With 19 minutes gone a slide-rule ball from Patrice Evra was nonchalantly flicked beyond Reina for the opener. "You two-faced bastards, your hero is Scouse," the Liverpool fans had taunted their opposite numbers about Wayne Rooney. But Old Trafford's darling now is actually a Dutchman.

5 Daniel Sturridge adds a dimension to Liverpool

On signing the forward the Liverpool manager said that his favoured position was playing through the middle as the main striker. The problem was what this might mean for Suárez who has shone when operating in the role. As the second half began an answer was offered as Suárez dropped back into the playmaker's role and Sturridge became the centre-forward, taking fewer than 15 minutes to display the requisite predatory instincts. When Gerrard's low shot was palmed out by David de Gea it was Sturridge who left Rafael flat-footed to score his first league goal for his latest club after last week's one in the FA Cup.