Wolfsburg make it seven signings in a week
Lopes (pictured) joined from Nacional Funchal and Sissoko, 20, from Portugal's Academica.
"Sissoko is a young man for the future," said controversial coach Magath who is often dubbed Quaelix - a combination of the German verb for torture and his Christian name.
Magath, also Wolfsburg's sporting director and known for his tough discipline and gruelling training sessions, was often criticised for his frantic transfer activity at previous club Schalke 04.
Since Christmas he has signed Franco-Ivorian forward Giovanni Sio, Portuguese midfielder Vieirinha, Czech midfielder Petr Jiracek, Serb midfielder Slobodan Medojevic and Macedonian forward Ferhan Hasani.
Magath, who led Wolfsburg to their first Bundesliga title in 2009, has had a less successful second stint after joining late last season.
Wolfsburg are 12th at the halfway point in the Bundesliga, four points clear of the relegation play-off spot.