ShareCeltic fell to a heavy defeat against Benfica in the Europa League, but Martin O'Neill is confident his side can bounce back.Martin O'Neill is confident his Celtic side can still reach the knockout rounds of the Europa League despite their defeat to Benfica.Celtic were thrashed 4-1 at Estadio da Luz after a brace from Jhon Duran and goals from Vangelis Pavlidis and Alexander Bah, leaving the Scottish side with 0 points after two games.Benfica took the lead after just five minutes as Duran won a penalty and scored a Panenka against Viljami Sinisalo; it is the earliest penalty goal Celtic have ever conceded in major European competition.Gianluca Prestianni then came to the fore, assisting Bah and Duran before half-time as Marco Silva's side were cruising to a big win.Camilo Duran managed to pull a goal back for Celtic, but Benfica still had the last say as Pavlidis scored in the 89th minute.In all competitions, Celtic have lost four of their last five games (W1) – as many as in their previous 36 games combined (W28 D4 L4).Celtic have also kept just five clean sheets in their last 54 major European matches, while they have kept just two in their last 30 in the Europa League.Nevertheless, O'Neill felt their second-half display provided reason for optimism, despite Benfica striking the woodwork twice after the break and creating more chances (14 shots to Celtic's nine)."Last thing you want to do is concede so early on. We could've capitulated, but I thought the second-half performance was terrific. We created chance after chance," O'Neill told TNT Sports."The second-half performance gives me the determination. I think we can still qualify. We can still do it."We came roaring back, the subs came on and did brilliantly. We could've scored a number of goals. It changed because two wide players really wanted to get at people."I accept on the break they could have scored themselves, as they did with their fourth goal."Celtic fell to a heavy defeat against Benfica in the Europa League, but Martin O'Neill is confident his side can bounce back.Martin O'Neill is confident his Celtic side can still reach the knockout rounds of the Europa League despite their defeat to Benfica.Celtic were thrashed 4-1 at Estadio da Luz after a brace from Jhon Duran and goals from Vangelis Pavlidis and Alexander Bah, leaving the Scottish side with 0 points after two games.Benfica took the lead after just five minutes as Duran won a penalty and scored a Panenka against Viljami Sinisalo; it is the earliest penalty goal Celtic have ever conceded in major European competition.Gianluca Prestianni then came to the fore, assisting Bah and Duran before half-time as Marco Silva's side were cruising to a big win.Camilo Duran managed to pull a goal back for Celtic, but Benfica still had the last say as Pavlidis scored in the 89th minute.In all competitions, Celtic have lost four of their last five games (W1) – as many as in their previous 36 games combined (W28 D4 L4).Celtic have also kept just five clean sheets in their last 54 major European matches, while they have kept just two in their last 30 in the Europa League.Nevertheless, O'Neill felt their second-half display provided reason for optimism, despite Benfica striking the woodwork twice after the break and creating more chances (14 shots to Celtic's nine)."Last thing you want to do is concede so early on. We could've capitulated, but I thought the second-half performance was terrific. We created chance after chance," O'Neill told TNT Sports."The second-half performance gives me the determination. I think we can still qualify. We can still do it."We came roaring back, the subs came on and did brilliantly. We could've scored a number of goals. It changed because two wide players really wanted to get at people."I accept on the break they could have scored themselves, as they did with their fourth goal."