Roberto Firmino was "frustrated" at missing out on Brazil's World Cup squad, but intends to use it as motivation.

The Liverpool forward was a surprise omission by head coach Tite for the tournament in Qatar, where Brazil were knocked out in the quarter-finals on penalties by Croatia.

Firmino had made a good start to the season at club level, scoring nine goals and recording four assists in 21 appearances (16 starts).

The 31-year-old put it down to being part of "God's plan", and hopes it can spur him on to improve further still.

"Of course it was frustrating not being called up to the World Cup but as I've said before, that's part of God's plan and I am following God's plan," he said to talkSPORT.

"It really does motivate me more and more not having gone to the World Cup, so I will work hard to get back into the Selecao."

Despite having time to rest during the World Cup, Firmino was unable to play in either of Liverpool's first two games back against Manchester City and Aston Villa due to illness, and is unlikely to feature in Friday's home clash with Leicester City either.

Roberto Firmino

However, the player suggested he should be fine beyond that and is soon to be back in training, adding further to manager Jurgen Klopp's attacking options.

"I'm already healed, thank God. I'll probably train tomorrow [Thursday]," Firmino added. "Then all being well I'll be ready, not for the next game [Leicester] but the one after that [away to Brentford on January 2]. So all great."

Liverpool had a shaky start to the season prior to the World Cup, winning just six of their 14 Premier League games (D4, L4), but won 3-1 at Aston Villa in their first league game post-World Cup on Monday.

The club also confirmed the signing of Dutch forward Cody Gakpo from PSV on Wednesday, which will go through on January 1 pending a work permit, and Firmino is confident the Reds can push on and put their previous woes behind them.

"Individually speaking, I started [the season] very well," he said. "Of course we, as a team, did not start the season well, but we are coming back.

"Thanks to the work we are doing, and our mentality of never giving up, we're now back and in form."