Winners 2-0 away from their first leg, Monaco and Benfica are in a strong position before their return leg on Tuesday in the third preliminary round of the Champions League, unlike Olympiakos.
On the Rock, Niko Kovac's players will have to confirm their success from the previous week against Sparta Prague.
But the Monegasques have meanwhile suffered a setback in the league, conceding a draw on Friday against Nantes (1-1).
If they pass the Czech obstacle, they will face Genk or more likely Shakhtar Donetsk, winner 2-1 in the first leg in Belgium.
Benfica started their championship better than Monaco (2-1 victory at Moreirense on Saturday) and will host Spartak Moscow on the strength of their success in Russia.
For Olympiakos and its French playmaker Mathieu Valbuena, the task promises to be more delicate after the draw conceded at home (1-1), against the Bulgarians of Ludogorets.
The Glasgow Rangers, coached by former Liverpool star Steven Gerrard, are also in danger: on the way to Sweden, Malmö surprised them 2-1.
Program of the second leg of the 3rd preliminary round of the Champions League, which will be played on Tuesday 10 August:
Tuesday August 10
(7:00 p.m.) FC Sheriff (MDA) - Red Star Belgrade (SRB) (Go: 1-1)
Slavia Prague (CZE) - Ferencváros (HUN) (0-2)
(7:30 p.m.) Shakhtar Donetsk (UKR) - Genk (BEL) (2-1)
(20h00) Ludogorets (BUL) - Olympiakos (GRE) (1-1)
Midtjylland (DEN) - PSV Eindhoven (NED) (0-3)
Monaco (FRA) - Sparta Prague (CZE ) (2-0)
(8:30 p.m.) Young Boys (SUI) - CFR Cluj (ROM) (1-1)
(9 p.m.) Legia Warsaw (POL) - Dinamo Zagreb (CRO) (1-1)
Glasgow Rangers (SCO) - Malmö (SWE) (1-2)
Benfica (POR) - Spartak Moscow (RUS) (2-0)
