Manchester United boss Ole Gunnar Solskjaer is working to improve Marcus Rashford behind the scenes at Old Trafford, according to reports. Rashford has endured a difficult Premier League campaign so far, scoring three times with two of those coming from the penalty spot. And the Athletic claim both Mourinho and Southgate believe the United star needs to improve his hold-up play with his back to goal. Mourinho is said to have doubted Rashford’s effectiveness from a centre-forward against teams who do not give United space. Furthermore, Southgate has publicly admitted the 21-year-old may not be at his blistering best from that position. And the report claims Solskjaer is now trying to improve Rashford at the club’s Carrington training complex. The England international has the backing of his manager despite his erratic season so far. Solskjaer has always supported the United hitman and, speaking recently, Rashford hailed his manager. The forward also took a sly dig at Mourinho by suggesting Solskjaer was better to play under because he used to play the sport himself. Asked by BBC Sport’s Gary Lineker how Solskjaer differs to Mourinho, Rashford explained: “He’s very different but it’s expected because he’s played. “Off the pitch he understand…