LIVERPOOL, England -- There were only 2,000 fans inside Anfield to celebrate Roberto Firmino's 90th-minute winner for Liverpool against Tottenham Hotspur, but the noise that the small crowd generated told you everything about the importance of the Brazilian forward's late header. Firmino knew too, as his celebratory run deep into his own half attested, while manager Jurgen Klopp's traditional post-victory fist-pumping tribute in front of The Kop produced almost as much energy as the night he went crazy after that famous Champions League semifinal win against Barcelona.

The fans, Firmino and Klopp celebrated in a big way because they all knew that this 2-1 victory carried great significance in what is likely to be a much closer title race than Liverpool's procession to the championship last season.

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It was a game decided by fine margins in a campaign that could see the title itself decided by such singular moments. The goal took Liverpool three points clear of Jose Mourinho's Spurs at the top of the table and emphasised their status as favourites to win back-to-back titles after finally ending the club's 30-year wait to be crowned champions of England earlier this year.

But while Mourinho will be criticised by the purists for his team's approach to the game -- Spurs were defensive, well organised and happy to use Son Heung-Min and Harry Kane as detached outlets -- Tottenham proved themselves to be genuine contenders against the best team in the country. This was Tottenham's first Premier League defeat since the opening-day loss at home to Everton and that unbeaten run has highlighted the progress the team has made since Mourinho took charge 13 months ago.

At Anfield, they underlined that progress by meeting the challenge of facing Liverpool. They frustrated Klopp's team, went close to taking the lead after Son had equalised Mohamed Salah's opening goal and generally gave as good as they got. Yes, the statistics will show that Liverpool dominated possession and created more chances, but football is, thankfully, about more than numbers on a chart and Tottenham's disciplined and obdurate performance offered proof that they can sustain a title challenge this season.

"We were playing to win, we were not playing to get a point," Mourinho said. "A point would have been quite a fair result, but we played to win and had the biggest chances to win it. The game was always under control. I feel it was a very undeserved result, but that's football."

Mourinho was stretching the truth to suggest his team created the better chances. Harry Kane went close twice and Steven Bergwijn hit the post, but Liverpool also hit the woodwork through Sadio Mane and all three forwards had good opportunities to score. But Mourinho was right to say that his team deserved a point, for their defensive performance if not for their swashbuckling attacking play. They weren't as negative as the anti-Mourinho brigade will claim, however.

Klopp described Spurs as a "counter-attacking monster" before saying Liverpool "massively deserved the three points" and insisting Son's goal was offside. The German's comments hinted at his relief at getting the win rather than offer a genuine reflection of the game, but ultimately, his team were the one that claimed all three points and Liverpool will look back on this game as, perhaps, the night that their title defence really slipped into gear.

Yet it could quite easily have gone the other way. Both Kane and Bergwijn went tantalisngly close to putting Spurs 2-1 ahead before Firmino's late goal.

Tottenham's missed chances and Firmino's late goal are the fine details that decide winners and losers, though, and Liverpool have developed a habit in recent seasons of capitalising on the key moments. This was the third successive season that they had scored in the 90th minute or later against Spurs at home. Liverpool know how to take advantage when it matters, but that is a lesson that Spurs have still to learn. They have become a stronger and more confident side under Mourinho, however, and their performance at Anfield showcased their growing maturity under the former Chelsea and Manchester United manager.

The £15 million summer signing of Pierre-Emile Hojbjerg from Southampton could turn out to be one of the bargains of the season, with the midfielder offering a reliable buffer in front of the back four. Hojbjerg's tenacity makes him a perfect Mourinho player and his work rate enabled Spurs to defend deep and use Kane and Son on the counterattack.

On this occasion, Mourinho's game plan did not get the reward it deserved, but the two clubs meet again at the Tottenham Hotspur Stadium at the end of January and Klopp will know that the game will be another major test of Liverpool's credentials. In that game, the fine margins could favour Tottenham and give them the title boost that this fixture has given to Liverpool.