Kilmarnock’s recent penchant for upsetting the Hearts fans continued as the Rugby Park side secured their passage to the Premier Sports Cup quarter-finals with a hard-fought win over Hearts. Innes Cameron’s first half header was enough to clinch a fifth successive victory for the Ayrshire outfit over their Edinburgh counterparts. What is more impressive is that they have now won six of their last seven games in Gorghie. Without a total of seven first team players through injury, Hearts were bereft of ideas in the final third. They were already also showing signs of fatigue amid a demanding run of 11 fixtures in 36 days. “It was frustrating," said Hearts manager Robbie Neilson. "We had loads of possession but didn’t really do a lot with it. “Killie scored the first goal with their first attack and that let them sit in and kill the game. “We just didn’t have that spark that we’d normally have. A culmination of a number of games back to back and all the effort that’s been put in, we’re asking players to go again and again. “Because of the injuries we’ve not had a chance to rotate and I think that had a big influence on the game. “So it’s about recruiting but also getting these guys ready for Saturday. “I don’t like to put a number on it in terms of new signings but you can see that we need a few to give us more. “You want to be in European football but it has its effects on players especially with the number of injuries we have. " Due to his personnel issues, Neilson elected to only name seven substitutes; among them were youngsters Aidan Denholm and Macaulay Tait. Alongside the three players (Boyce, Nathaniel Atkinson and Kye Rowles) who picked up injuries in the weekend’s Premiership victory over St Johnstone, Craig Halkett, Stephen Kingsley, Jorge Grant and long-term absentee Beni Baningime were also unavailable. With three centre backs missing, Alex Cochrane was asked to partner 19-year-old Lewis Neilson in defence. Despite signing Christian Doidge on loan from Hibernian earlier in the day, Kilmarnock were not able to call on the Welshman due to the striker playing in the competition for his parent club at the start of the season. McInnes opted for Cameron in attack ahead of the experienced Kyle Lafferty and the visiting boss would have been pleased by his team’s bright start. Kilmarnock gave as good as they got and forced Hearts goalkeeper Craig Gordon into action after only eight minutes. Rory McKenzie picked up a pass on the edge of the area and his fierce drive was beaten away by the Scotland international. The pace of Barrie McKay, Josh Ginnelly and Alan Forrest kept Kilmarnock on their toes at the other end but the away team dealt comfortably with what Hearts threw at them. Indeed, it was McInnes’ side who broke the deadlock after 21 minutes with a fine finish from Cameron. The towering forward peeled off Hearts defender Michael Smith at the back post and sent Danny Armstrong's inviting delivery back across goal and into the corner of the net past the stationary Gordon. Before the half was over Hearts striker Lawrence Shankland did manage to get an effort on target with a glancing header from Andy Halliday’s cross but it was a good height for Sam Walker to repel. Hearts tried to exert more pressure after the break but continued to lack a cutting edge. In fact, it was the Rugby Park side who went the closest to scoring. Ash Taylor's looping header from Liam Polworth's corner came back off the bar. “I’m delighted," said Killie boss McInnes, whose side will face Dundee United in the last eight. “Hearts at the top end of the pitch, outwith the Old Firm, are next in line in terms of asking questions of you. “I’m impressed with the squad Robbie has put together. I know they had their issues but they still put a strong team out. “And to get a clean sheet against that lot of talent you need to do a lot right. We should take a lot of confidence from that. " On the draw, he added: “It’s a home tie, it gives us an opportunity and Dundee United will see it exactly the same way. ".