Rangers are aiming for their fourth consecutive league victory as they host St Mirren at Ibrox, while Celtic look to keep their perfect domestic record intact in their match against St Johnstone. The Old Firm, consisting of Rangers and Celtic, are set to face each other in the quarter-finals of the Premier Sports Cup on Sunday. This clash is significant as both teams aim to build momentum ahead of their first derby of the season, which is expected to be a high-stakes encounter. Rangers are currently behind third-placed St Mirren on goal difference, after St Mirren started the season strongly. Craig McLeish, the head coach of St Mirren, has been praised for introducing a more fluid playing style and was named Premiership manager of the month for August. McLeish expressed confidence in his team's internal belief but admitted that results could have been better. However, St Mirren will be missing Paul Nsio, who is ineligible to play against his parent club, Rangers, which could impact their performance in the match. Rangers continued their winning streak with a recent victory over Motherwell, following wins against Aberdeen and Falkirk. Head coach Derek McInnes said confidence is growing within the team, but he emphasized that the pressure to achieve success remains until a trophy is won. The injury to Lawrence Shankland, a key striker who had been performing well, is a setback. Additionally, Kevin Kelsy may struggle to adapt to his new role without the luxury of a gradual transition. Celtic secured a win in Paisley despite not playing at their best, with Yang Hyun-jun scoring the decisive goal. However, Yang is now away with South Korea for the Asian Games, which means the team will need to reshuffle its lineup. Martin O'Neill, Celtic's head coach, may be cautious about moving Camilo Duran out wide again, given his strong form, and might instead start Shim Mheuka, the on-loan striker from Chelsea. Striker Kasper Hogh and left-back Kieran Tierney are also nearing their return from injury, which could provide a boost to the team. St Johnstone, aiming for a third consecutive league win, will face Celtic at McDiarmid Park. Head coach Simo Valakari acknowledged the need for both skill and a bit of luck to beat Celtic, but he praised his team's commitment to playing attractive football. The Saints have a strong central defensive partnership in Cheick Diabate and Zach Mitchell, though they have yet to keep a clean sheet in the league. O'Neill noted the vitality of St Johnstone's approach, drawing comparisons to McLeish's tactics at St Mirren, highlighting the competitive nature of the upcoming match.