Scotland defender Russell Martin feels they have struggled to shake off their Euro 2016 disappointment - but claims victory over Slovenia would spark a revival.A 5-1 win in Malta in their opening World Cup qualifier suggested Scotland had put their loss to Georgia and a fourth-placed finish in the Euro 2016 preliminaries behind them, but it proved a false dawnThey have since scored only once, conceding seven, and taken one point from games Lithuania, Slovakia and England to leave them in fifth spot in Group F, four points behind second-placed Slovenia.Martin said: "I think the disappointment of not qualifying, when we played so well for the majority of the campaign, and one result probably cost us. I think that is disappointing for people and it's tough to take and we maybe haven't quite got over that quickly enough."But performances haven't been terrible. We have been one or two passes away, where it was clicking earlier on in the last campaign. We have been a fraction off it. But there's no one reason. If there was one reason, we would have rectified it."But we are working hard. Everyone still believes in what the manager wants to do."The most important thing is, regardless of what's gone on in the last three or four games, if we win on Sunday, we are right back in the mix and have a right chance of moving on up the group and qualifying. "We need a little spark in this campaign and hopefully Sunday will be it." For some fans, the spark would come from a change in management but Martin refuses to countenance the consequences of defeat for Gordon Strachan."For me personally I don't think about that," the Norwich player said. "I think we are going to win the game and we move on from there. Obviously that's a bridge we'll have to cross if we don't get the result that we want."But the manager has been fantastic to me and a lot of the lads in the squad. He has given most of us a chance, a lot of caps, and a few lads in the squad have played with him before."Everyone enjoys working with him, everyone likes him, and we need to make sure we show that on Sunday and put in a performance to make sure there are no question marks after Sunday, where we are going and where we are heading in the campaign."Hampden is expected to be little over half full for the crucial encounter but Martin is confident they will not let any subdued atmosphere affect their performance.The 31-year-old added: "Hopefully we put in a performance that makes sure next time we play it's full up."There's been a lot of negativity around the last couple of results, which we understand, this is football."But we've got a big game on Sunday, everyone needs to come together - fans, staff, players, media, everyone needs to be positive towards Sunday so we can get a result. After Sunday, say what you want."After starting 16 of the previous 17 qualifiers - a meaningless game against Gibraltar the only exception - Martin was dropped for November's 3-0 defeat by England.A space has opened up in defence after injury to Grant Hanley, but Christophe Berra and Charlie Mulgrew started in Wednesday's 1-1 friendly draw with Canada.Martin said: "I had played most qualifiers under the manager so to miss out on such a big one against England, I would be lying if I said it was easy to take."It was disappointing but you respect it and keep working hard knowing that this was coming up and another big one in June."The key is to play well for your club to get here in the first place and then, when you're up here, is making sure you show how hungry you are to be playing and make sure you are worthy of a place in the team."