Sanchez produced a moment of brilliance to put Arsenal ahead and guide them to a 3-1 Group H win over visiting Cologne on Thursday, after kick-off was delayed by an hour due to crowd congestion at the Emirates Stadium.
The soon-to-be free agent – who missed the start of the campaign through injury – has cut a frustrated figure this season, having seen his reported move to Premier League rivals Manchester City fall through before the transfer window closed but he issued a reminder of his undoubted quality in London.
"We had a slow start and there was accidental goal. After that, it was important not to concede and panic and put more pace into our game. From then. we controlled the game and won convincingly in the end," Wenger told BT Sport.
"I think Sanchez is still running after his best form. He is a fantastic football player but physically he has just come back. But he has it in his locker to do something special, which he did.
"We want to do well in all the best competitions and I had an experienced team today, even though I made nine changes. They are all top-class players. There is no hierarchy in the squad."
It was not an ideal start for Arsenal after a reported 20,000 Cologne fans descended on London despite only 3,000 tickets being available.
When the match finally got underway, Arsenal found themselves trailing early following Jhon Cordoba's stunning 40-yard strike in the ninth minute.
Substitute Sead Kolasinac breathed life back into Arsenal with his 49th-minute equaliser before Sanchez gave the hosts the lead 18 minutes later.
Full-back Hector Bellerin put the result beyond doubt nine minutes from the end and the Spain international added: "It is a new competition for us so we had to set the tone. We think we are one of the best teams in the competition so we have to show that on the pitch.
"I am very happy with the victory. We were ready to play at 20:05 BST but these things happen. We started a bit with cold feet but after that it just worked."