The former PSV star and ex Tottenham captain both caught the eye in what was an ultimately poor result against Doncaster Rovers.
Though their first matches for the Black Cats ended in a disappointing 2-0 defeat, both players demonstrated that they will be good players for Dick Advocaat's side this season.
Cedric Evina and Harry Forrester scored the goals for Paul Dickov's side at the Keepmoat Stadium, but there were positives for the visitors in the shape of their new arrivals.
Dutch international Lens started the match and looked very lively, causing lots of problems in the Rovers defence, while Kaboul came on at half time, and ended up captaining the side as Advocaat changed his side around. Sebastien Coates also featured for the first time since making his move to the Stadium of Light permanent.
If Lens can bring some attacking quality to the side, and Kaboul some leadership and defensive strength to the back line, both players will prove to be superb pieces of business by Sunderland, as they seek to avoid the relegation dogfights that have blighted their last few seasons.