Attacker O’Halloran has been St Johnstone’s key attacking weapon this season, providing pace and intelligent running to what has been a very attacking Saints side this term.While he’s been the talk of the January transfer window his core numbers, four goals and five assists, fail to do justice to his impact on his team. O’Halloran’s direct style drives St Johnstone up the field and creates opportunities for team-mates as witnessed in recent matches against Celtic.The task of stopping O’Halloran will fall to Lewis Stevenson, who after years as an Easter Road utility man has finally established himself as the club’s left-back. Able to play as a wing back and as part of a back four, Stevenson provides width should Alan Stubbs opt for a diamond midfield formation. Liam Henderson and Simon Lappin. SNSOn-loan Celtic midfielder Henderson has showed signs of his undoubted potential in recent weeks, helping to turn the match against Falkirk back in Hibs’ favour as well as scoring a wonderful free-kick against St Mirren. The build up may have been overshadowed by a Tynecastle ticket row but Saturday’s League Cup semi-final between Hibernian and St Johnstone provides several intriguing match ups.Tommy Wright’s side continue to perform well in the top flight but face the Championship high flyers, who have claimed the scalps of Aberdeen and Dundee United.While Saints switch between a 4-4-2 and 4-2-3-1, Stubbs’ Hibernian have experimented with 3-5-2, 4-4-2 and 4-3-3 in recent weeks.Here are some of the vital battles that could play a major part in deciding the outcome of this weekend’s last four clash. Michael O’Halloran may be up against Lewis Stevenson. SNS Comfortable on the ball and technically astute, it would be a surprise if the 19-year-old wasn’t included in the starting line up where he is likely to come into contact with St Johnstone’s Simon Lappin.With Murray Davidson and Chris Millar rated at 50/50, Lappin may be deployed in a holding midfield role alongside Liam Craig. Lappin fits the St Johnstone stereotype as astute, effective and underrated with the 33-year-old possessing a wicked shot from distance.St Johnstone’s defence will come up against Hibernian’s attack. SNS Stubbs may be tempted to try out his new look partnership of Jason Cummings and Anthony Stokes after the Irishman made a scoring cameo on his second Hibs debut. Both forwards have a tendency to drift wide in search of the ball in an attempt to drag centre backs out of position.While Wright reckons captain Dave Mackay will recover from a hip injury in time to partner Steven Anderson in the centre of defence. Injuries and personal changes have contributed to Saints’ defensive record which has seen them concede 34 league goals already this term, the same total as in the whole of last season.While Mackay is more mobile than the experienced Anderson both will be keen to avoid being drawn into one-on-one situations especially on the wings.Paul Hanlon will have to pay close attention to Steven MacLean. SNS One of the Scottish Premiership’s most intelligent forwards, regular readers of this site will be well versed in our admiration for St Johnstone’s Steven MacLean.Back in October the forward was averaging a top flight goal every 63 minutes and while his rate has slowed since then, he was back on track in Saturday’s loss at Celtic Park. MacLean, who has proved to be a cup specialist for Saints, has scored 11 goals this term including eight from inside the six-yard box.The 33-year-old’s movement opened up space for Michael O’Halloran to shine in the 3-1 win over Rangers at Ibrox before hitting the winning goal against Morton in the last round.Paul Hanlon may be tasked with keeping tabs on the former Sheffield Wednesday attacker and he will be keen to make it an aerial contest rather than a race on the ground.