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James Forrest admits that he will have to "keep at it" for Celtic to keep his place in the team, now that Patrick Roberts has returned

Winger James Forrest attributes part of Scotland's success against Lithuania and Malta to the fitness and winning habit of the squad's Celtic contingent.

Forrest began both World Cup qualifiers beside five Celtic team-mates - Craig Gordon, Kieran Tierney, Scott Brown, Stuart Armstrong and Leigh Griffiths.

"It's been a factor; we train with each other day in, day out," said Forrest.

"We've had a lot of games since the start of the season and I think that has helped as well."

Forrest was keen to highlight the contribution to the Scotland team of all the squad members, not just his club-mates, who have gone 53 domestic games unbeaten.

And he knows that with Scotland having matches against Slovakia at Hampden and Slovenia away early next month, they will almost certainly have to win both to clinch one of the eight runners-up spots to reach next summer's finals in Russia.

"Once it comes back around, we will try to take care of the two games," said 26-year-old Forrest of the remaining Group F games.

"The Slovakia home game will be really important. We will need to win that. We have put ourselves in with a chance but we need to be ready for both games."

Six Celtic players lined up for Scotland against Malta at Hampden - Craig Gordon, James Forrest (back row, 1st and 2nd from left), Leigh Griffiths (back row 2nd from right), Stuart Armstrong, Scott Brown (front row, 2nd and 3rd from left) and Kieran Tierney (front row, right)

Celtic had to cut short their summer break to play in Champions League qualifiers against Linfield and Rosenborg before the domestic season began, but Forrest believes this has aided Gordon Strachan and the national team.

"We've had a lot of games since the start of the season and I think that has helped," he said.

"We were back in early for pre-season so we were up to speed pretty quick because of the Champions League games.

"All the boys are feeling confident. Getting into the Champions League was a massive boost and we've had a couple of good results with Scotland.

"I think we've got seven more games with Celtic before we go back to Scotland so hopefully we can keep it going.

"I think the Champions League experience, playing against top players and teams, will help us.

"We just need to keep the confidence high and keep going."

Forrest has a fight on his hands to keep his place in the Celtic starting line-up now that Patrick Roberts has returned on a season-long loan, but the Englishman's arrival is one he welcomes.

"Paddy was here for 18 months before," Forrest explained. "A massive club like Celtic is always looking to make the squad stronger so it's good to have competition for places.

"Last year we both had spells and the manager changed it.

"This year has started well for me. I just want to keep going and keep playing.

"The squad is really strong here. The gaffer will know when to change it and keep it fresh.

"At Celtic you have two or three players at international level for each position. Every player knows that they need to keep at it or they won't be playing."