"Theo at the moment is in a kind of mental state where he knows he can affect the game when he comes on," coach Arsene Wenger was quoted as saying by the club's website.

The 17-year-old forward took the pitch in the 75th minute when Arsenal were tied 1-1 by the Germans.

He dished out two assists for Emmanuel Eboue and substitute Julio Baptista as the Londoners remained in the race for qualification.

Arsenal dominated the game following conceding a stunning goal as early as the fourth minute but failed to level the score in the first-half with Alexander Hleb hitting the cross bar from a Cesc Fabregas' defense-splitting pass.

But Fabregas fed Robin van Persie for the equalizer seven minutes after re-start and the Spaniard believes Walcott provided the team with the extra push needed for the victory.

"Theo was fantastic when he came on, he really made a difference," said Fabregas, who at only 19, praised Walcott's maturity.

"It takes time when you are young. Sometimes the manager doesn't want to pick you because of the pressure," UEFA.com quoted him as saying.

"But Theo's a great player and I'm sure he will play many games for Arsenal."

Walcott, who became the youngest player in England's history to play for the national side, replaced veteran winger Freddie Ljungberg on the left flank before moving across the pitch to set up the two winning goals.

"I started him first on the left and then I felt that he did not really get in the game," Wenger said.

"Baptista was comfortable on the left with Theo on the right. You could see straight away that when he went to the right it made a big difference."

Arsenal are now split Group G summit with Porto as both teams have 10 points, while CSKA Moscow are third on seven points.

All of the three teams still have chances to qualify to the next round as Hamburg lie in the basement of the group with no points.