Alex Song has caused irritation at Arsenal with his desire to explore his transfer market options in the face of interest from a clutch of leading clubs, including Barcelona. The midfielder has been made aware that he is in demand after a positive season last time out and he wants to listen to what is on offer.

But his stance has gone down badly with the manager, Arsène Wenger, and the board, who feel that Song ought merely to have ignored the approaches to his representatives and continued to show gratitude for what the club has done for him. Wenger took Song as a teenager from Bastia in a deal that was initially worth £350,000 and has developed him into a defensive midfielder of repute.

The friction has built to the point where Wenger has questioned Song's worth to the team and even wondered whether he may sell him if a large offer were to come in. Arsenal have not yet received any official bids.

The club's move for Real Madrid's Nuri Sahin has been motivated, in part, by the developing situation with Song. Wenger wants Sahin, the 23-year-old Turkey midfielder, on a season-long loan with the option to make the transfer permanent. Song is under contract until 2015.

Wenger arrived in Germany on Monday for a training camp with a 24-man squad which included Santi Cazorla and Robin van Persie. He has been given special dispensation by Málaga to incorporate Cazorla in his preparations even though the midfielder's transfer from the Spanish club has still not been announced. Cazorla passed his medical at Arsenal last Thursday, with his personal terms and the basic fee of £16m having been agreed.

The friendly with FC Köln on Sunday stands to feature several eye-catching storylines. There will be the Arsenal debut of Lukas Podolski against the club he left at the end of last season for £10.9m, while Olivier Giroud, the £13m signing from Montpellier and, possibly, Cazorla will play their first minutes in Arsenal colours. It would be a sight for some sore eyes if Van Persie were also involved.

Andrey Arshavin, who has travelled to Germany with the squad, is the subject of a £4m bid from Galatasaray. The winger, who is out of contract next summer, is also of interest to Queens Park Rangers and clubs in the Middle East.