All three controlled their fate after inspiring results in the quarterfinals on Thursday, keeping Portugal on course to feature three semifinalists for the first time in 17 years.
Porto, the new Portuguese league champion, routed visiting Spartak Moscow 5-1, Benfica dealt to PSV Eindhoven 4-1, and Braga drew with Dynamo Kiev 1-1 but earned an all-important away goal.
In the other quarterfinal, Villarreal, the only representative from Europe's so-called big five leagues, crushed Dutch league leader FC Twente 5-1.
The second legs are next Thursday.
Radamel Falcao scored a hat trick for Porto, and Silvestre Varela and Maicon added to the home crowd's happiness in Dragon Stadium.
Falcao's three goals, two of them headers, lifted his tournament-leading tally to 10.
Even though Porto celebrated its fifth Portuguese league title in six years last Sunday, it showed no hangover effect.
After Falcao sneaked in behind the defense at the far post to convert Alvaro Pereira's skipping cross for the 37th-minute opener, Porto relaxed and let loose.
After the return leg in Moscow next week, it is likely to face Villarreal in the last four.
Villarreal's joy was tempered by defender Gonzalo Rodriguez breaking his leg in a second-half tackle from behind by substitute Marc Janko. Rodriguez was immediately taken to hospital, but Janko played on and scored Twente's consolation goal in injury time.
Nilmar scored twice for Villarreal, and defender Carlos Marchena, Borja Valero, and Giuseppe Rossi also hit the back of the net.
In a rematch of the 1988 European Cup final, the result didn't go PSV's way this time, as Benfica put on a show, especially in the first half.
Pablo Aimar put the host ahead in the 37th minute, then Eduardo Salvio scored on each side of halftime.
Zakaria Labyad pounced on a fumble by Benfica goalkeeper Roberto Gago a minute after going on as a 79th-minute substitute for out-of-form striker Marcus Berg, but Javier Saviola stretched Benfica's lead back to three in injury time.
"They outclassed us in the first half," PSV coach Fred Rutten said. "In the second half they relaxed after the 3-0 and that allowed us to play." Braga left Kiev with a 1-1 draw thanks to a Dynamo own goal.
Andriy Yarmolenko headed Dynamo into the lead after only six minutes, but Oleh Husev, who set up that goal, also deflected one into his own net in the 13th.
Dynamo looked the more enterprising side but its hopes were limited after substitute Andriy Shevchenko was sent off in the 61st for his second yellow card.
Shevchenko rounded the goalkeeper and shot into the goal, but apparently didn't hear the offside whistle, and was sent off.
"I didn't hear the whistle. The goalkeeper didn't hear it either and played on," Shevchenko said.
