Arsene Wenger is impressed by the way Alex Song has transformed his game during his time at Arsenal.
Song, traditionally a defensive midfielder or centre-back, once again showed his knack for going forward when he scored a last-gasp winner for the Gunners as they edged out West Ham 1-0 on Saturday.
That goal marked the Cameroon international's fourth of the season and third in three games, and manager Wenger has praised his progression since he arrived at the Emirates Stadium four years ago.
"Song wants to get forward. Sometimes defensive midfielders just want to defend," said Wenger.
"It's not just his main role. He does it well in fairness. He came here as a centre-back, maybe he will finish centre-forward.
"He sees there is big competition in midfield and that helps. Nobody is guaranteed a place.
"We've had so many good players and so many players who have become exceptional here but, at the moment, Song is moving forward."
Frenchman Wenger feels much of 23-year-old Song's development is down to an improvement in his fitness.
"Song has improved his engine," he added. "Before he was less mobile. He has improved his mobility.
"He doesn't need a breather now when he goes and comes back.
"Since he has more stamina capacity, when we win the ball, he is on the move straight away and, when his timing is good, he arrives at the right moment in the box.
"He is now a good trainer but this was not always the case. That's why he has improved."