The 0-0 stalemate at St James' Park means Liverpool go into the New Year with a three-point lead over Manchester United, having played a game more.
Mohamed Salah gave an interview in Spain last week in which he said Barcelona and Real Madrid were top clubs and "who knows what will happen in the future".
Premier League: Dominant Liverpool hammer Crystal Palace 7-0; Arsenal’s crisis worsens with Everton defeat
Jurgen Klopp's champions — despite being dogged by injuries this season — are five points clear of neighbours Everton after humiliating Palace 7-0 at Selhurst Park.
Premier League: Liverpool frustrated by VAR as Brighton snatch late equaliser; Leeds United beat Everton
The draw ensured Liverpool will finish Saturday back on top of the standings, with Tottenham able to reclaim first place by avoiding defeat at Chelsea on Sunday.
Firmino has never been viewed as a pure finisher, but criticism of his lack of goals has grown in recent months.
The Egypt forward twice tested positive for COVID-19 during the international break and missed the 3-0 win over Leicester in the Premier League on Sunday.
Premier League: Top clubs will struggle with injuries without changes to fixture list, says Liverpool's Jurgen Klopp
Klopp's men saw off Leicester City 3-0 in Sunday's late Premier League kick-off and will welcome Atlanta to Anfield in the Champions League on Wednesday before travelling to Brighton for Saturday's early kick-off.
Medical swabs on the national team "showed that our international player, Mohamed Salah, Liverpool star, was infected with the coronavirus", it said in a tweet, adding he was "not suffering from any symptoms".
Premier League: Kevin de Bruyne misses penalty as Manchester City, Liverpool share spoils; Kane nets 150th goal in Spurs' win
Kane headed in a late winner in a 1-0 victory against struggling West Brom to lift Jose Mourinho's side above Southampton after their fourth win in five league games.
City returned to winning ways after an indifferent start to the season, courtesy of a first-half goal from Raheem Sterling, who condemned Arsenal to their seventh straight defeat in league matches between the two sides.
Premier League: Ollie Watkins scores first-half hat-trick as Aston Villa hit seven in drubbing of Liverpool
Ollie Watkins scored a first-half hat-trick as the Reds became the first reigning English champions to concede seven goals in a league match since 1953.
Premier League: Diogo Jota scores first Liverpool goal as champions beat Arsenal; Fulham fall to third straight defeat
The champions' high-risk, high-reward strategy paid off in their come-from-behind 3-1 win over Arsenal on Monday in an open game featuring a late clinching goal by Diogo Jota in his first league start for Liverpool.
Premier League: From Thiago vs Xhaka to Salah vs Tierney, player battles where Liverpool-Arsenal will be won and lost
The toughest test of what Arsenal can aim for this season comes on Tuesday with a trip to Anfield, where Liverpool have not lost in 60 league games.
The Egypt international, who signed a new five-year deal in 2018, was the top scorer at the club this season with 17 Premier League goals as they secured a 19th top-flight title with seven games to spare.
Premier League: Under Jurgen Klopp of Germany, Liverpool fans re-discover what it is to be Liverpudlian
To paraphrase Bill Shankly — Liverpool was made for Jurgen Klopp from Glatten, Germany (whose coat of arms, incidentally, is the steering wheel of a ship), and Jurgen Klopp was made for Liverpool.
Premier League: Faltering restart for Liverpool title charge after shutdown; Chelsea secure comeback win at Aston Villa
With eight games still remaining, Liverpool has plenty of breathing space to end the drought and win its first domestic championship since 1990.
Premier League: Leaders Liverpool step up preparations with big win over Blackburn Rovers in warm-ups
Liverpool's first-team regulars Sadio Mane, Naby Keita and Joel Matip got their names on the scoresheet along with Takumi Minamino and youngsters Ki-Jana Hoever and Leighton Clarkson in a convincing win over the Championship side.
Premier League: Liverpool recover from early scare to beat Bournemouth; super-sub Alexander Lacazette scores as Arsenal win
A scare survived this time, and Liverpool moved closer to lifting the Premier League trophy.
Premier League: Leaders Liverpool announce pre-tax profit of $54.57 million after Champions League-winning campaign
Liverpool signed goalkeeper Alisson and midfielders Naby Keita, Fabinho and Xherdan Shaqiri during the accounting period and offered new deals to 11 players
Premier League: Liverpool fight back against West Ham to win five-goal thriller, need 12 points to lift maiden title in PL era
Trailing 2-1 late in the second half, West Ham keeper Lukasz Fabianski was twice at fault as Mohamed Salah and Sadio Mane ensured Liverpool prevailed to equal the record of 18 consecutive top-flight wins set by Manchester City in 2017.