"Darren is a classic Steady Eddie player. He's just what we require at the moment," Lennie told the Western Mail.
"He is better defending than he is attacking - and that's music to my ears because we've got to stop conceding goals. Darren has played in many positions for Sunderland, in defence and in midfield, but I think right-back is his best position.
"He has joined us on a month's loan but we might end up making it a permanent signing. He is in the last year of his contract at Sunderland who have already got a very good right-back in Steve Wright."
Williams, who will be given squad No. 24 (vacated by Gareth Whalley), has England U21 international experience. He goes straight into the squad for this Saturdays trip to Wolves.