Arsenal take been without Koscielny, 31, for their past two games, while 34-year-old Cech last procrastinated for the Gunners in the defeat at West Brom a month ago.
Both veterans around into the XI at the Riverside tonight.
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And Wenger accepts Arsenal, who have won just one game during their pair’s non-attendance, have missed their experience.
“We were a bit nervous because recently the gang (have) had some bad experiences,” Wenger said before kick off.
“(Cech and Koscielny) play a joke on the experience and the stature to cope with the pressure that the team is lower than drunk.
“So that should help.”
Arsenal need a win tonight to move following into sixth place as they chase a top-four finish.
As for Middlesbrough, they are six points off protection with seven games remaining to save their Premier Ally status.