Arsenal defender Laurent Koscielny feels Alexis Sanchez is nearly unstoppable with the ball at his feet following the Chile international's double in Tuesday's 3-0 Champions League win over Dinamo Zagreb.
The 26-year-old has already netted nine goals in 19 appearances for the Gunners in 2015-16 and Koscielny is impressed by his team-mate's fine performances.
"Alexis is interesting when he plays with the ball," the France international told Arsenal's website.
"With the runs [he makes] he's very important because he's so quick.
"For the defence, it's very hard to defend against him."
Arsenal will qualify for the knockout stages of the if they beat Olympiacos by two goals in their final Group F match and Koscielny was relieved to still be in contention.
"It was important to win because we didn't start well in the group stage," he added.
"It was our chance to [remain in with a chance of] qualifying for the next round, so we needed to play well and to score goals.
"We kept a clean sheet so that's very important because the last result was not good. Now we have a chance to qualify for the next round."