Michael O'Neill could make two changes for this midweek encounter with central midfielder Joe Allen and experienced striker Steven Fletcher both set for returns. Tyrese Campbell continues to build up his fitness following a serious knee injury, while Nick Powell is ruled out with a thigh injury. Centre-back Liam Kitching serves the second instalment of his three-match ban this weekend. An injury to left-wing-back Ben Williams means that Clarke Odour could be shifted into a more defensive role with Aaron Leya Isaka making his first start for the Tykes out wide. Mads Andersen, Carlton Morris and Jordan Williams are also unavailable for the visitors.