LONDON, July 25 (Xinhua) -- English Premier League side Bolton got defence strengthened Saturday in the signings of Aston Villa defender Zat Knight and Hull full-back Sam Ricketts on three-year deals.

    Center-back Knight, who has won two England caps, has struggled for regular first team since joining Villa in 2007 from Fulham, starting just 13 Premier League games last season.

    Wales international Ricketts, who can play on the left or the right of a back four, started 27 Premier League games in their first top flight season.

    They are Wanderers boss Gary Megson's third and fourth signings of the summer, with the club having brought in Sean Davis after his contract at

    Portsmouth expired and also defender Paul Robinson from West Brom.

    Bolton is also close to bringing in South Korea international midfielder Lee Chung-Yong from FC Seoul.

    The 21-year-old has spent the past week in the north of England, where according to the K-League side Lee reached a verbal agreement on a three-year deal for a transfer fee of about 2.1 million pounds (three million dollars).