Substitute Alex Mowatt made an instant impact as Oxford United made it back-to-back wins with a 1-0 victory over Blackpool.Mowatt came off the bench in the 78th minute and his first touch was to send over a free-kick that Jon Obika met with a glancing header for the winner - his seventh goal of the season.But the result was harsh on the Seasiders, who were denied by four fine saves from keeper Simon Eastwood.Oxford missed a golden opportunity in the 10th minute when Gino van Kessel selfishly went alone as he and strike partner Wes Thomas bore down on goal.A simple square pass would have surely led to a goal, but Van Kessel thought he could score, only for keeper Christoffer Mafoumbi to dispossess him.Eastwood tipped over Clark Robertson's left-foot drive and then blocked a volley from right-back Kelvin Mellor.The U's keeper also saved well from Colin Daniel's shot, before pushing over Viv Solomon-Otabor's 20-yarder, and another fierce drive from Robertson.