Roma failed to reach the Champions League group stage after having two men sent off in a 3-0 defeat at home to Porto in the second leg of their playoff on Tuesday.Roma had drawn the first leg 1-1 after Thomas Vermaelen was sent off and it was again made to pay for poor discipline as Daniele De Rossi was dismissed in the 39th minute and Emerson Palmieri, followed him five minutes after halftime.Despite the numerical disadvantage, Roma pushed hard but could not cancel out Felipe Augusto’s early opener and two goals in as many minutes from Miguel Layun and Jesus Corona sealed matters. (Also read: Former Porto boss Julen Lopetegui named new Spain coach)”We had prepared for it well, but we started badly,” Roma midfielder Kevin Strootman said. “We played one game in 10 and the other in nine. It could be a mental problem because physically we are fine. We knew what we had to do on the pitch, but we didn’t do it. We didn’t play well and I don’t know why.”Though Roma tried to turn the game around, Strootman pinpointed Layun’s strike as the definitive blow.”Even with nine men we tried everything,” he said. “But when we went 2-0 down it was all over. Now it’s difficult to get back up, we are all angry. But we have to think about the league because we have to do better. No one is to blame, we lost together.”Monaco beat Villarreal 1-0 to advance to the 32-team group-stage draw in Monaco on Thursday following a 3-1 aggregate victory. Celtic also squeezed through despite a 2-0 loss to Champions League newcomer Hapoel Beer Sheva, after winning the first leg 5-2.advertisementThere was no fairytale for Irish side Dundalk after a 1-1 draw at 10-man Legia Warsaw, which progressed 3-1 on aggregate to reach the group stage for the first time in 21 years.Ludogorets Razgrad drew 2-2 at Viktoria Plzen to advance 4-2 on aggregate.Italian clubs have failed in the playoffs for five of the last six seasons, typically leaving Serie A with only two representatives among Europe’s elite.Roma was looking to end that streak but went behind after less than eight minutes as Felipe was left unmarked at the back post to head in Otavio’s free kick. Roma’s chances of progressing diminished when De Rossi, who was being played in defense, was sent off for a rash tackle on Maxi Pereira.Coach Luciano Spalletti took off Leandro Paredes to introduce Emerson but the Brazilian was also shown a straight red card for a horrendous challenge on Corona. Roma upped the pressure but goalkeeper Wojciech Szczesny gifted Porto its second of the night in the 73rd minute. Caught out in no-man’s land on a Porto counterattack, Layun rounded him far out from his goal before firing across into the empty net. (Also read: Chelsea confirm Mohamed Salah sale to AS Roma)Corona scored the third moments later, when he blasted past Szczesny at the near post.Villarreal was hoping to overturn a 2-1 first-leg defeat and ensure Spain once again had five teams in the group-stage draw.But Monaco dominated and Fabinho scored from the spot after Mateo Musacchio handled the ball in the area.Celtic had lost in the playoff round for the past two seasons and the perennial Scottish champion almost threw away the tie despite a commanding first-leg advantage.Saidy Janko tripped Ovidiu Hoban to concede a penalty in the 15th minute, although television replays indicated that the foul was outside the area.Celtic goalkeeper Craig Gordon saved Maharan Radi’s spot-kick but swiftly went from hero to villain.Six minutes later Gordon, and defender Kieran Tierney got in each other’s way, allowing Ben Sahar’s header to squeeze past them into the net.Another defensive mix-up three minutes after the break, this time between Gordon and Janko, led to the ball spilling out of the goalkeeper’s hands and allowing Hoban a tap-in. The blunder ensured a nervy 42 minutes for Celtic.The losing teams go into the Europa League group stage.