Jürgen Klopp insists "really important" Lucas Leiva won't leave Liverpool in January transfer window

Liverpool manager Jürgen Klopp insists Lucas Leiva will not be leaving the club this month and declared he remains a "really important" player in the squad.

The long-serving Brazilian scored his first goal in 2,316 days - or 201 games - as he headed the match-winner from a Philippe Coutinho corner kick in the first-half of the Reds' 1-0 FA Cup third round replay win over League Two side Plymouth Argyle.

That strike at Home Park was just Lucas' seventh goal in 10 years on Merseyside, and his first since September 2010, and comes in the middle of another month in which his future has been much speculated about.

Lucas, who turned 30 earlier this month, had been close to a move to Inter Milan in early January - only for deal to stall after the Serie A side refused to commit to signing the player permanently in the summer.

Klopp, asked whether Lucas would remain at Liverpool in his post-match press conference at Plymouth, told reporters: "We have a kind of an agreement, so I would say yes."

It is thought the German, due to Lucas' service to the club and the respect that demands, is happy to honour the midfielder-turned-centre-back's wishes for more regular first-team football if the right offer arrives.

Lucas is a wonderful guy, insists Klopp

Asked about his value to the squad, and his header being his first goal for the club in seven years, Klopp joked that in training he is "the top scorer of all" in a particular drill they do "after each last training [session] before a game" where they "finish with old versus young."

"So I'm really surprised that he didn't score for that long," said a bemused Reds boss, adding that he is "back on track" now and hailing Lucas as "a great personality", "a good player" and "a really wonderful guy."

Klopp even suggested that he is "pretty sure" that Lucas "could be a good friend for the rest of your life when he is not a player" and added: "You have to line up and sometimes not - it's not his hobby to accept things like this [not playing regularly] but he's okay. And he is really important for us."

The Reds' No.21 has only started three of their 21 Premier League games so far this season, despite starting all but one of their seven fixtures in domestic cup competitions.

He is likely to prove vital while Liverpool await FIFA's decision on Joel Matip to hear whether the Cameroonian is eligible to play while his national team are in action in Gabon.

Matip remains caught in a wrangle with the Cameroon FA after rejecting the chance to represent his country at the Africa Cup of Nations - despite having not played for the Indomitable Lions since September 2015.

FIFA will return to Liverpool on Friday with a decision as to whether they will open a case on the dispute, which would mean a further 7-10 day wait for the Reds - in which time they play three games.

Lucas will also likely get another opportunity to lead the team out as captain in the club's FA Cup fourth round clash against Championship opponents Wolves at Anfield on January 28.