Arsenal centre-back Laurent Koscielny hobbled away from the training session after picking up a knock to his right ankle, and was unable to rejoin before it ended.
The severity of Koscielny's injury is unknown at present, but on immediate assessment by the medical team it was decided it was best to take him back inside while Arsene Wenger looked on in worry.
Goalkeeper Wojciech Szczesny missed the session entirely after picking up a back strain since his arrival in Japan, an issue he has had before.
Like Koscielny, the Arsenal 'keeper missed out on the 3-1 win against Nagoya Grampus Eight, who Wenger managed for a period before joining the north London side.
This comes after Thomas Vermaelen's injury - a fracture in his back - which will keep the Belgian sidelined for around three months.
Vermaelen's injury would have surely pushed Wenger in to thinking about signing someone at centre-back, but the weekend's incident would surely have highlighted the issue should one of his first choice defenders get injured at any stage before November.
Signing a centre-back has now become more of a priority, with squad depth imperative if Arsenal are to challenge for trophies. Injuries and a lack of replacements is an excuse that Arsenal fans have heard all too much of in the past.
Swansea's Ashley Williams has reportedly admitted his interest in a move to the Emirates, but the £10 million asking price is thought to have put Wenger off. It remains to be seen if he will pursue someone else, or return to the Swansea captain and try to negotiate a deal.
One of these things needs to be done.
Additionally, Olivier Giroud sat of training for a short period of time after a calf problem, but came back on towards the latter stages to quash any doubts on his fitness. The Frenchman scored in the friendly against the Japanese club.
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