John Hartson knows he has caused much amusement in football circles in the past 12 months as a player with a most unusual passing problem. He is incapable, so it would seem, of passing a routine medical.

Even Coventry City, who signed him from Wimbledon just over three weeks ago, could not give his right knee a bill of health clean enough to satisfy their insurers, which is how they came up with the ingenious plan to pay a £15,000 instalment for every game he plays, rising to a maximum £500,000.

But if the rest of football has been doubled up in laughter the disappointments of the past year have caused real pain for Hartson, most poignantly when his proposed transfer to Rangers fell through last September. In fairness he never hinted that he wanted to leave Wimbledon when they were relegated from the Premiership last season.

He has been the victim of modern football's ruthless financial structure, in which the Premiership clubs commandeer a vastly unequal slice of the TV millions. He says: "When Wimbledon went down, it became obvious the club's Norwegian owners wanted me off the wage bill. In the end they were panicking, thinking: `He's failed three medicals, we're not going to get any money for him.' And Terry (Burton, the manager) was reluctant to play me because he knew I would probably be on my way.

"No disrespect to Tottenham but I wasn't too upset when they pulled out of a deal last April because I'd just had an operation and wasn't really ready for them. But I was devastated when Rangers decided not to go ahead. I'd pulled out of a Wales game to fly up there and there were hundreds of supporters to meet me. I said to my missus, bloody hell, I fancy this and I was so ready for a new culture, a new environment, that I agreed terms straight away."

Hartson took out his frustration on some of the English League First Division's whipping boys, scoring twice against both Sheffield Wednesday and Huddersfield on his next two appearances, which also said much for his professionalism. Earlier this season a move to Charlton was also mooted but the asking price of £5 million was so high as to exclude negotiation.

To add to his frustration Hartson insists that the battles of his wounded knee have been greatly exaggerated. He says: "There must be something that comes up on a scan which frightens the doctors but I don't think any footballer's knee would be a pretty sight. A heck of a fuss has been made about my knee but it's perfectly okay and I have more niggles with my ankles, thighs and hamstrings."

He does not want to shout about that too loudly. But because of his previous disappointments he admits that, when he arrived for his medical at Coventry, he felt nervous. The compromise over money finally allowed the move to be completed and Hartson overlooked Coventry's precarious league position because of his respect for the manager Gordon Strachan.

Hartson was robbed of a debut goal against his former club West Ham which was disallowed for a phantom foul but scuffed one in against Charlton last week which would have delighted Coventry, if only because such a messy effort suggested that the rub of the green might finally be going their way.

He says: "I'm sure Ian Rush got a few of those in his time. And I know I will score goals, I always have at all my clubs. I'm not one of those forwards who gets the ball in space and thinks, oh no, I'm not sure I'll put this away. If I get the chances, I'll score."

Strachan said he signed Hartson as he wanted someone on his team sheet who frightens opponents. As everyone knows, Hartson managed to frighten even his team-mates with that infamous incident at West Ham involving Eyal Berkovic.

He says: "I probably frighten the gaffer because he's only 5ft 3in. But I take his words as a compliment. When I see the names of Sol Campbell or Ugo Ehiogu on a team sheet, I say to myself, `I'm going to have a game today, I am going to have a battle."'

On his way back to London from training the other day, Hartson was approached by a Coventry fan in a service station who said he thought it was unfair that there was so much pressure on him. Hartson, though, believes the pay-as-he-plays deal removes all the pressure.

He is reluctant to tempt fate by making that most dangerous of assessments, that his new team are too good to go down. But as evidence of the quality in the squad he points to the absentees on the training pitch this week caused by international demands.

If his team-mates can provide the ammunition, he is confident he can score the goals that will allow Coventry to extend their 34-year stay in the top flight. He says: "I can't produce miracles and I'm not Roy of the Rovers. I can't beat 10 men and then knock the ball past the keeper. But I'll give 100 per cent effort on the field and the training pitch and I'll get my share of goals."

If Coventry do go down, he will probably find himself at a club where his wages are again unsustainable. But should he rescue them, he may yet realise his dream of playing at Ibrox. He says: "I'm not the sort to lie awake at night saying please come back in for me, Rangers. But you never say never in football."