Vermaelen, who signed a new deal at Arsenal earlier this week, has been out for over a month with an ankle injury.
"Vermaelen will be back in full training on Friday," Wenger told the club's official website. "It is ten days to two weeks for him.
"Diaby is getting better but is not available to play yet. He's probably back in around two weeks - he is just a fraction behind Vermaelen."
Meanwhile, the North London club are still unclear as to how long Carl Jenkinson will be sidelined for after the full-back suffered a knee problem in the Gunners' 1-0 win over Marseille in the Champions League this week.
"We don't know yet but it is very unlikely he will be available for Sunday," Wenger added. "He is having a scan and we will know some time on Friday."
The Gunners take on Stoke City in the Premier League this weekend.