Rennes wasted the chance to move level on points with Monaco and Marseille at the top of the league after squandering a two-goal lead.
The 24-year-old Alioui, who honed his skills at Monaco's academy, is getting his first taste of the top league in France this season.
After Rennes dominated the first half and took command of the match with goals from Ludovic Blas and Chirstopher Wooh, Alioui revived Le Havre's hopes with a header past goalkeeper Steve Mandanda five minutes before the interval.
Le Havre's chances took another blow near the hour mark with Samuel Grandsir's sending off, but Alioui managed to snatch another goal in the 70th minute. Well set up by Loic Nego's pass, Alioui made the most of some slack defending to curl a right-footed shot into the back of the net.
Rennes lags two points behind Monaco and Marseille in the standings after taking five points from its three opening matches. Le Havre, which was promoted to Ligue 1 in June, has two points.
The Malta midfielder, who joined Reims from Belgian side Union Saint-Gilloise this summer, scored two impressive goals with his left foot to complete the 3-1 win after Yunis Abdelhamid's opener in the eighth minute.
Teuma got his first goal from a free kick near the edge of the area and then beat goalkeeper Benjamin Lecomte with a powerful half-volley under the bar.
Jordan winger Mousa Al Tamari scored Montpellier's goal, taking his tally to three goals in as many games.
Reims has six points, two more than Montpellier.
AP soccer: https://apnews.com/hub/soccer
The Associated Press