The Chile international scored his 13th goal of the season as he helped the Gunners book their place in the Champions League knockout stage courtesy of a 2-0 victory over Borussia Dortmund.
He’ll show great enthusiasm – that will be infectious to the lesser lights in that Arsenal squad
And the Liverpool legend described Sanchez, who moved to The Emirates in a £35m deal from Barcelona in the summer, as a priceless member of Arsene Wenger’s squad.
“He’s a real plus for Arsenal this year,” Souness told Sky Sports.
“He’s getting all types of goals, and on top of his goals he makes other people play because he’s infectious.
“He has perpetual motion, he never gives up on any cause, and you can see what his goals mean to him. He lives and breathes football and it must be an absolute delight to play with him, and that makes other people play.
“If you’ve got somebody turning up every day for training – he’ll be first in the group, doing all the running properly, he’ll show great enthusiasm – that will be infectious to the lesser lights in that Arsenal squad, the younger players, the ones that maybe don’t have the same attitude.
“Players like him are priceless in your group.”
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