Wenger hopes that Johnson can make his young guns invincible

Olivier Giroud casts a quizzical eye towards photographers at a training session watched by Michael Johnson (Getty Images)

As one of the great athletes of the last two decades, Michael Johnson represented the notion of invincibility in sport long before the great unbeaten Arsenal team of 2003-2004 reached similar heights, although it was an Arsenal squad of rather more modest ambitions that the American watched train yesterday.

Johnson, was a guest before tonight's Champions League game against Olympiakos, the Greek champions. Arsène Wenger has started sending some young players to Johnson's athletic performance school just outside Dallas, Texas, in the summer to improve their strength and power.

Arsenal's Spanish defender Ignasi Miquel was the most recent. Had he come back noticeably different? "Yes," Wenger said, "but not fast enough to win a gold medal.

"You have two ways to run quickly. I will teach you now," Wenger said. "First is to do your movement as quickly as possible but you gain that very quickly. You will not improve that at the age of 18. The second is to have more power on your push [off from the ground]. That is quite logical."

Sadly for Miquel, he was not even among the 18 Arsenal players who trained yesterday. After defeat at home to Chelsea on Saturday, there are some decisions to be made.

Abou Diaby is out, with Wenger blaming the player's problems – he came off after 17 minutes of the Chelsea game – partly on France calling him up in the last international break. "I said many times that if France wanted Diaby in Spain they should not take him for the Finland and Belarus games," he said.

Roy Hodgson is due at the Emirates tonight, partly to watch Carl Jenkinson, who is still holding out for an England call-up amid strong interest from Finland, for whom he played Under-21 football.

Mikel Arteta did not train yesterday and a decision between him and Francis Coquelin will be made today. Olivier Giroud could start, but Gervinho is a more likely striker. Giroud scored against Coventry City in the Capital One Cup, but it does not seem to have registered with Wenger. "Once the first [goal] goes in maybe the rest will follow," the manager said.

Wenger will continue with Vito Mannone in goal tonight, with Wojciech Szczesny likely to be out for another two weeks. Roy Carroll, the former Manchester United goalkeeper, may start for Olympiakos.