Liverpool star Alexander Isak has suffered another injury blow with Sweden, forcing him to withdraw from international duty.The forward, who has enjoyed his best-ever start to a Premier League season, will be assessed by Liverpool’s medical staff at the AXA Training Centre. He scored in Sweden’s 2-1 win over Romania on Friday but was spotted after with a blood-soaked sock after a heavy challenge.’You can see it… It was a heavy stamp,’ he told reporters in the mixed zone. ‘Those of you who have played might know that it takes a few minutes for the pain to subside, but it was okay.’ While it appears minor on the surface, Liverpool fans will have their fingers crossed that Isak does not suffer the same fate as last season, when he missed 30 matches for club and country due to various injuries. Alexander Isak has withdrawn from Sweden duty with a ‘minor injury’ after a ‘heavy stamp’ He has enjoyed a fine start to the Premier League campaign, scoring four goals in five gamesThe £125million record signing suffered a broken leg and was sidelined for months after a robust challenge by Tottenham’s Micky van de Ven in December.It left him unavailable until April and unable to gain any momentum in a debut season where he scored just four times in all competitions after signing from Newcastle. He has started this season much more like himself, banging in four goals in five Premier League games, a personal best start to the campaign. The 27-year-old scored in the 2-2 draw against Nottingham Forest, struck both goals in the 2-0 win over Ipswich, and netted the 1-0 winner against Bournemouth. Sweden’s statement on his exit described the injury as ‘minor’, but it means he will play no part in their upcoming Nations League games against Poland, Bosnia and Herzegovina, and Romania. Alongside scoring goals, Liverpool manager Andoni Iraola wants Isak to step up by leading Liverpool’s press with more ferocity.Daily Mail Sport has reported how Iraola has even been showing Isak clips of academy graduate Lewis Koumas as a model of off-the-ball work. Isak seems to be getting the message, telling BBC Sport recently that defending is an ‘attacking weapon’.