Morocco striker Chamakh - a free transfer from Bordeaux - produced a neat finish to put the Barclays Premier League side ahead just before the break, while Koscielny, the former Lorient centre-back signed in a £10million deal, looked assured alongside Thomas Vermaelen.
Wenger's young Gunners were, however, eventually pegged back following several changes when Pato nodded in a free-kick with 14 minutes left and tomorrow face the challenge of Celtic, who drew 2-2 against Lyon earlier.
"Chamakh had good presence up front, and played a good intelligent game. He and Koscielny did very well," said Wenger.
"We wanted a player up front who can play for the team and works hard, who can go into combinations and at the back, someone who was calm, can read the game and play the ball out.
"Of course it is only one game, but their attitude in training is very good and they can only improve."
Wenger continued: "It was a good test for us, we have come back from a very hard working camp and you could see that some legs were still not completely refreshed.
"We were in trouble a bit for the last 20 minutes because we shuffled the team around, but overall we looked very solid defensively and dangerous going forwards.
"The only thing I would say is there was a lack of communication from the free-kick, you did not feel anybody took charge of the organisation."