Liverpool manager Jurgen Klopp said Lucas Leiva will remain with the club after the Brazilian veteran's goal secured a 1-0 FA Cup third-round replay victory at fourth-tier Plymouth Argyle on Wednesday.

Lucas, Liverpool's stand-in captain, scored his first goal in seven years to see off the League Two Pilgrims at Home Park.

Afterward, Klopp quashed speculation linking Lucas with a January transfer to Italian giant Inter Milan.

When asked if Lucas would definitely be staying with Liverpool this season, Klopp replied: "From my point of view, I think yes he is staying.

"But what is definite in this business? We have kind of an agreement, so I actually would say yes.

"Lucas is a very valuable player. He's a great personality and a good player. He's a really wonderful guy. He is really important for us."

Lucas, a 2007 signing from Brazil's Gremio when Rafa Benitez was in charge at Anfield, converted Philippe Coutinho's 18th-minute corner with a near-post header to give Liverpool victory over Argyle, which had held the Reds 0-0 at Anfield in the first meeting.

It was the 30-year-old's first goal since a Europa League tie with Steaua Bucharest in September 2010 and Klopp expressed surprise at his drought.

"We have been playing old against young each time after training and Luca is the top scorer of the old team," Klopp said.

"So I am really surprised that he had not scored in so long, but now he's back on track."

Coutinho boost

Klopp is especially satisfied to see Coutinho ease his way toward full fitness after an ankle injury.

The former Inter Milan playmaker, who was in sensational form at the start of the campaign, started a game for the first time since Liverpool's 2-0 win over Sunder-land in late November.

"It was good and I am really happy," said Klopp, whose side will host second-tier Wolverhampton Wanderers in round four.

"It was really important for us. He played 60 minutes and it was the perfect intensity, so it's good for him and for us."

Klopp defended making wholesale changes to the starting XI that drew 1-1 with Manchester United on Sunday, saying it would be "idiotic" to retain the same side due to Liverpool's congested schedule.

"We had a lot of young players and one of the challenges was that they were playing live on television against a fourth-division side," Klopp said.

"Everyone thinks you're three or four classes better and you're feeling embarrassment when you lose a challenge. We fixed that at half-time, but it was a tough game."

It could have been uncomfortable for Klopp had Jake Jervis' acrobatic volley hit the net rather than a Liverpool post in the 75th minute.

The tension rose further when Reds striker Divock Origi's penalty was saved in the closing stages by Luke McCormick after Yann Songo'o fouled Alberto Moreno, but Lucas' goal proved enough to see off the southwestern side.

"We gave them a good run for their money and I feel we've put our club back on the map over the two ties," said Pilgrims boss Derek Adams.