Alan Shearer has challenged Obafemi Martins to demonstrate his commitment to Newcastle United in the most tangible manner and play through gritted teeth for the rest of the season. The Nigeria striker provoked consternation last Saturday when he reported a groin problem on the morning of the club’s Barclays Premier League match away to Stoke City and, although that matter has been resolved, others have still to be addressed.

Since Shearer’s appointment as manager, greater discipline and punctuality have been insisted upon. In an attempt to tackle Newcastle’s dreadful record with injuries and fitness, he has decided that players receiving treatment must stay at the training ground late into the afternoon. The messages may be basic, but they are having an effect.

“I’ve enjoyed the challenge of dealing with different characters,” Shearer said. “You’ve got 22 players who are all different. The manager’s job is to get the best out of them. What you say to players and what you don’t say to them is very important. Some need a kick up the backside or pushed harder than others. I don’t know whether it’s fate or the 4 o’clock thing but a lot of those injuries are clearing up.”

A scan on Martins’s groin has revealed that “there is something not right in there,” Shearer said, and although the forward is rated increasingly unlikely to be fit for Sunday’s match away to Tottenham Hotspur, the club are hoping that he will make himself available for the five games that follow. However, Mark Viduka is back in the squad after an Achilles injury, helping to make up for Martins’s likely absence.

“We have a few different scenarios with Oba,” Shearer said. “One, an operation; two, an injection; three, rest; and four, play through the pain barrier. We know what we want him to do, it is just a case of how much pain that will cause him.”