With a deal for the South Korea striker Park Chu-young wrapped up, Arsenal are on the verge of signing two new defenders as Arsène Wenger seeks to rebuild his back-line following Sunday's humiliating 8-2 destruction at Manchester United. The German international centre-back Per Mertesacker is in advanced talks over a £10m transfer from Werder Bremen and is likely to be joined at the Emirates by the Brazilian left-back André Santos, who has undergone a medical at Arsenal ahead of a potential £6m move from Fenerbahce.

The move for Mertesacker, who flew into London on Tuesday to put the finishing touches on an expected three-year contract, seems aimed at repairing some of the most obvious defensive flaws that Arsenal supporters have long decried: as the holder of 75 Germany caps the 26-year-old offers a wealth of experience and organisational know-how that would enable him to a bring a measure of stability to a side that seems increasingly prone to lapses into chaos.

Mertesacker's composure on the ball is matched by his precision in the tackle – he is considered one of the cleanest tacklers in Germany and rarely receives bookings: such an influence would be welcome on a team that has had a player sent off in every Premier League match of the season so far.

Mertesacker would also add formidable aerial power. Standing at 6ft 6in, he is a powerful presence at set pieces at both ends of the pitch. Arsenal conceded 53.3% of their goals from set pieces last season, a higher proportion than any other team in the Premier League.

Santos will bring much-needed strength to the left-back position. The sale of Gaël Clichy to Manchester City and the injury to Kieran Gibbs has left Wenger so short of options that on Sunday he had to call on Armand Traoré, who has since moved to Queens Park Rangers on a three-year deal.

Park, meanwhile, will wear the No9 shirt at Arsenal after joining from Monaco. "I just want to show how good I am and prove myself," the 26-year-old South Korea captain said. "In my opinion this is a great club, now I have to show what I can do on the pitch. I will never give up, I will show heart, I will give everything and I hope [the fans] will support me."

Arsenal have been linked with a host of other names ahead of Wednesday's transfer deadline, including the Chelsea trio Florent Malouda, Alex and Yossi Benayoun.