Towards the end of an illustrious career during which Joe Mercer won the English league and FA Cup as a player for both Everton and Arsenal, and managed Manchester City to the first division title, he said: "Genius is great when it's on song. When it goes off, it contaminates."

Old Joe was a classy midfielder in the period that straddled World War II. He put a smile on the face of football, and is remembered fondly in two mosaics at City's Etihad ground and a wall mural at Arsenal's Emirates Stadium.

The player he had in mind when he made that observation was George Best.

But, if Old Joe was still with us, I rather fancy that Mesut Ozil and Alexis Sanchez would catch his eye. They also surely fit his comment about genius.

Ozil, the strolling minstrel, has neither great pace nor much of a fighting spirit. However, his passes can tear an opponent, any opponent, to shreds. Sanchez has all the heart and speed you could desire, and indefatigable thirst to play and to win.

Alas, Arsenal have seen little of virtue from either man this season.

Little, indeed, since last February and March when last season imploded for the Gunners against Bayern Munich in the Champions League. A 1-5 defeat in Munich, and 1-5 again in London, devastated the team, the club and in particular the two main stars.

It was known, even then, that Ozil and Sanchez, and their so-called advisers, were agitating for salary increases.

They wanted, we were told, £300,000 ($538,000) per week. Or else? Or else they wanted to play for some other club that would meet their demands.

Sanchez, we all know, has a suitor in Manchester City who would pay what he asks. And whatever is written about gentlemen's agreements or the rule about one club not attempting to procure a rival's player while he is under contract, the Sanchez-to-City move appeared sealed.

Ozil? Where are the takers?

We hear incessantly that Inter Milan, or even Besiktas, are admirers of the German who has Turkish heritage. Half the Bundesliga would possibly also covet his silky skills, but not on the wage level that he thinks he is worth.

So, Ozil is in limbo. Recently he has become a non-playing sulk around the club. One other admirer, from their time together at Real Madrid, is Jose Mourinho.

"If you were expecting Ozil to be super aggressive, that is not Mesut," Mourinho said. "If on the contrary you expect him to make the ball smile every time he touches it, there is Ozil.

"Every pass, the ball goes in the right direction, at the right speed and with the right intensity."

So, Ozil to United in the next window? Mourinho is not saying yeah or nay.

Meanwhile, what use are reluctant stars to Arsenal, and what is the evidence that they are earning even the wage they signed up for at the start of their contracts?

Martin Keown and Ian Wright, former Gunners now in the TV studios and newspaper columns, have come out and accused the pair of downing tools.

Tacitly they accuse Arsene Wenger, their old "governor", of being too loyal. And it's true that Wenger never publicly criticises his players.

The manager is of the old school, the Joe Mercer school, in believing that you praise gifted players, you coax them and do not tell the world that they are mercenaries.

Lately, though, the genius going off song line has seemed appropriate. Ozil, 28, helped Germany to win the last World Cup and helped his country's 100 per cent run to qualify for the next one. Has he helped his club?

Last season he scored 12 times and made 14 assists. This season he has made only five appearances and neither scored nor assisted. He has barely figured since the 0-4 surrender of Arsenal at Liverpool at the end of August, and Wenger has cited a knee injury.

Sanchez, also 28, has also had limited playing time. He was given leave at the start of the season because his country, Chile, represented South America at the Confederations Cup in Russia.

Chile had twice won the Copa America, inspired by Sanchez. But, following the 0-3 defeat in Brazil on Wednesday, Chile have failed to qualify for the 2018 World Cup.

"I watched Brazil versus Chile," Wenger said on Friday. "It was a physical game and mentally I will have to assess the situation when Alexis gets back. I must say, he got some special treatment in terms of fouls."

In the past, no one could ever doubt that Sanchez wanted to play, sometimes even when he is half-fit and travel weary. "Alexis is in a difficult state of mind," Wenger added. "He expected to go to the World Cup. In every generation a player carries the pressure of expectation of a nation.

"In France it was Zidane. In England it was Beckham. In Chile, it is Sanchez. I have no doubt Sanchez wants to perform. He never goes onto the pitch to lose, never."

So two different characters, two different pay-rebels.

Wenger had believed he could talk them around, re-ignite their fire and their value to the team.

That belief is now under pressure of time. Wenger has had to rebuild team morale without the self-important two. Danny Welbeck, Alex Iwobi and (when fit) Jack Wilshere do not between them approach the artistry of Ozil and Sanchez.

But at least they are willing. At least they buy into the team culture that has restored a semblance of Arsenal quality to their league play.

Maybe it is one last shot from Wenger, maybe the manager is preparing a fire sale of the two stars in the January window.

When he was directly asked if selling them in January was now an option, he replied: "Once you are in our kind of situation, we have envisaged every kind of solution. Yes, it's possible."

Even Wenger, a coach in love with his players, must smell the contamination that affects team morale when genius goes off.