Kilmarnock boosted their Premiership survival hopes with a crucial 2-0 victory at home to Ross County. The win, coupled with results elsewhere, moves the Rugby Park side nine points clear of basement boys St Johnstone with four games to play. It was no more than the hosts deserved after they dominated the contest from the moment they took a 36th minute lead. Both sides had until that point produced a nervy and error-laden contest but it turned in Killie's favour when Bruce Anderson nodded a Danny Armstrong cross into the net. From then on, they could - and should - have scored more than just one more. That arrived in the 69th minute as Liam Donnelly popped up to casually find the bottom corner in a packed penalty box. A host of other chances were missed, while at the other end the Staggies created next to nothing as Killie got their post-split fixtures underway with a pivotal three points. They were dealt injury blows beforehand as Joe Wright picked up a knock in training and wasn't risked, while Matty Kennedy suffered a recurrence to his niggling back injury that kept him for an extended period earlier in the campaign. And their plans were inhibited further just before kick-off when Brad Lyons was removed from the starting line-up, replaced by David Watson. There was a return, however, for club captain Kyle Vassell who made the bench just days after gaffer Derek McInnes suggested he may miss the remainder of the season. The opening exchanges reflected the stakes for both sides as neither set of players appeared able to shake off nerves with errant passes and poor touches being prevalent. Indeed, it took 35 minutes for the first incident of note to happen. Terrific footwork from Bobby Wales down the left flank saw him evade a couple of challenges before the ball was played out to Armstrong on the opposite side. The winger cut in and fired a fizzing effort that flew narrowly passed the far corner. The spark that provided was immediate because Killie were in front within 60 seconds. Armstrong's delivery to the back post was nodded home by the leaping Anderson - who escaped his marker and took his tally into double figures for the season. That eased the pressure on the hosts, who played with a bit more freedom and confidence as they searched for a second. It nearly arrived in the early stages of the second half when Donnelly met Fraser Murray's corner with a glancing header that flew wide of Jordan Amissah's right-hand post. Killie looked to turn the screw and created a number of chances they were unable to take. Armstrong saw his strike from a tight angle turned behind before firing another attempt over while Amissah produced a terrific save to deny Corrie Ndaba as the full-back raced through. It appeared only a matter of time before the second arrived. And it duly did so on 69 minutes when Donnelly showed calmness and compsoure inside a congested penalty box to poke home his first goal of the campaign. It was no more than the Ayrshire outfit deserved for a second half display in which they were in near total control from start to finish. There was never any danger of Don Cowie's side forcing their way back into the game as Killie saw out the remainder of the contest with relative ease and took a step closer to preserving their top flight status. Kilmarnock: O'Hara; Mayo, Findlay, Deas, Ndaba; Armstrong (Ramsay 80), Watson, Donnelly, Murray (McKenzie 86); Anderson (Watkins 80), Wales (Cameron 90). Subs not used: McCrorie, Vassell, Mackay-Steven, Polworth. Goal: Anderson (37), Donnelly (69). Ross County: Amissah; Tomkinson, Lopata (Efete 45), Campbell; Wright, Randall, Kenneh (Samuel 53), Allardice (Nisbet 59), Ashworth (Phillips 76); Hale, Wright. Subs not used: Ross, Brown, Grieves, Harmon, Smith.