Andrew Robertson believes Scotland can finish their 2018 World Cup qualification campaign with the four wins they might well need to get to Russia.The Scots were denied a famous and much-needed win Group F against England at Hampden Park on Saturday when Harry Kane made it 2-2 in added time after two quick-fire free-kicks from Leigh Griffiths had overturned Alex Oxlade-Chamberlain's opener for the Three Lions. With six fixtures played, Gareth Southgate's side remain six points ahead of the fourth-placed Scots who trail Slovenia by three points and Slovakia by four with games running out.Gordon Strachan's side travel to Lithuania on September 1 before a home game against Malta three days later, finishing off the section in October with the visit of Slovakia and a trip to Slovenia.There is little if any margin for error remaining but the Hull defender remains confident:Robertson said: "If you look at the fixtures we have got, we are capable of beating them all if we can perform like that (against England)."Slovakia away (0-3) and Lithuania at home (1-1) were disappointing performances, we are not hiding away from that."But if we can up that performance by 10 or 20 per cent then I believe we have got the better of them and hopefully we can get beat the other two teams that we have already got points from"The boys are disappointed because we know what it could have been."We have four games left and we know what we have to do."If we can put performances in like we did against England and Slovenia (1-0 win in March) then I think we will get the Tartan Army right behind us and if we do, Hampden is never a good place to come to."I thought the fans were magnificent and they gave us that extra 10 per cent when we needed it."Robertson admitted a measure of culpability at Kane's goal where, after midfielder Stuart Armstrong had conceded possession when a break was on, the Spurs striker was unmarked and able to knock a cross from Raheem Sterling past keeper Craig Gordon.The former Dundee United player said: "I think we had a four versus two and we could have killed the game off. We gave it away cheap and it went out wide."It was one of those crosses, a tough one."He is in between me and Charlie (Mulgrew) and it is a good height that maybe Craigy could have come out but all three of us have maybe got to look at ourselves, that we could have done a bit better, we were all a bit uncertain."It was disappointing but like I said, maybe at the start we would have taken the draw."Scotland keeper Gordon accentuated the positives from a thrilling encounter, saying: "It is still a point and we probably would have taken that before the start."We can't be too disappointed about it."The manner it came about was not what we would have liked but if it was the other way round and we scored at the death it would have been a good point."We don't know how many points it will take so we got into each game trying to win it and see where it takes us."