Leigh Griffiths admits he needs to learn to relax if he is to finally bag his first goal for Scotland.The Celtic hitman has been a prolific scorer at club level but has failed to find the net in 11 appearances at international level.The man who hit 40 goals for the Hoops last term confessed he has been snatching at chances for Scotland, because he has been trying too hard to make his mark for his country.Manager Gordon Strachan could do with the striker rediscovering his scoring touch when they face Slovenia in Sunday's make-or-break World Cup qualifier.Griffiths said: "Maybe I am trying too hard and I just need to relax a little bit more."I want to try and break my duck for Scotland as quickly as possible. It's frustrating for a striker, not scoring."But it's not about me. It's about the team and how I can help them to get the three points."Am I a bit rusty right now? Yeah, but as a striker you need to be ready whether you're starting the game or coming off the bench."The gaffer has kept us on our toes this week with the tempo of training. Whoever he gives that number nine jersey to will be fully focused on doing a job."Griffiths has not always been trusted by Strachan to lead the line for Scotland.The 26-year-old was given just 15 minutes of action during the whole of the nation's failed Euro 2016 qualifying campaign.But the Parkhead forward insists he and his team-mates still owe a debt of gratitude to Strachan and hope a result this weekend will settle the bill. "There's a lot of things said about the gaffer that is probably unfair," Griffiths said. "We as players need to take on that criticism as well."Everybody loves coming away with Scotland and playing for the gaffer."I've seen things with people saying he should resign and this and that."But us as players, we want to get a good win and three points, which would put us just a point behind Slovenia with the England game coming up in the summer."We still feel we're going in the right direction under the gaffer. Everyone is still playing for the same cause. We want to get to the World Cup as much as anybody."The results recently haven't been good but one win (on Sunday night) changes everything."Strachan accepts Scotland can kiss goodbye to their hopes of reaching Russia 2018 if they do not see off the Slovenians.But Griffiths has warned the Tartan Army not to expect an all-out assault.He said: "The fans have got to be patient with us. We've got a game-plan and we'll stick to that."Hopefully that is enough, at the end of the day. In football you always need a bit of luck but we have got enough in this squad to get the win."