Letsie Koapeng drew first blood when he converted a penalty in the 25th minute after goalkeeper Mbongeni Mzimela felled City talisman Lebogang Manyama in the area.
Patosi then bagged his first goal for the Citizens with a smart turn and finish on the hour-mark, moments before fellow new signing Modise made his debut off the bench as a replacement for Mpho Matsi.
Modise didn't take long to announce his presence, tapping home the third goal in the 72nd minute after being teed up by man of the match Lyle Lakay.
Dikwena reduced the deficit 10 minutes later via a close-range header from Robert Ng'ambi, but the visitors failed to make further inroads as they lost a second straight match under new coach Peter Butler.
Benni McCarthy's men, who beat champions Bidvest Wits 1-0 in their Premiership opener, will revive hostilities with the Students in the semi-finals of the MTN8 at Cape Town Stadium on Sunday, having edged Polokwane City 1-0 in the last-eight.
Stars, who lost 2-0 to Maritzburg United in their first league game, next visit SuperSport United on September 13.