Martin O'Neill is targeting victory over Scotland in June to ignite the Republic of Ireland's bid to make the Euro 2016 finals.
Shane Long's last-gasp equaliser snatched a 1-1 draw with Group D leaders Poland at the Aviva Stadium on Sunday night and kept alive Ireland's hopes of claiming one of the two automatic qualification places.
However, they now sit in fourth place in the group - three points behind the Poles and two adrift of Germany and the Scots, making the showdown with Gordon Strachan's side in Dublin crucial.
O'Neill said: "Naturally, it's a very, very important game. I think we'd have to beat Scotland. I think it probably just boils down to that - we have to win that game.
"If the second-half showing is anything to go by, I think we are capable of doing it.
"Whatever we may lack, courage and spirit are not among them. I don't think it's a fluke now that we have scored late goals in games. That's three times now we have scored recently in the last few moments. We also hit the bar against Scotland.
"I know they are cliched phrases, but it does show something about the character of the team. At least we keep going right to the end, and who knows? Who knows, (the draw against Poland) might be an important point."
Slawomir Peszko looked to have maintained Poland's charge towards the finals with his 26th-minute strike giving them an advantage they maintained until stoppage time at the end of the game.
However, having twice been rescued by the post as first Robbie Brady and then Robbie Keane were denied, substitute Long stabbed home a priceless 91st-minute equaliser to rescue a point and keep Ireland's hopes of a top-two finish alive.
O'Neill, who saw John O'Shea deny Germany in similar fashion in October, said: "We started off tentatively in the game. We were a little bit nervous and, just when we started to get into the game we conceded, from our viewpoint, a very poor goal which puts you on the back foot.
"But our second-half performance was simply terrific. We dominated from the 45th minute to the 90th and we put Poland on the back foot. We created a number of chances - we certainly deserved at least a draw in the game, and perhaps we could easily have won it maybe if there had been a few more minutes left.
"We got the momentum going, the crowd stayed with us throughout - I thought they were terrific - and we are still in the competition."
Poland boss Adam Nawalka was understandably disappointed to see his side succumb at the death, but pleased with the performance.
Nawalka said: "We won a point at a very difficult ground to play at, so we are happy. Of course, we conceded a goal in added time and that definitely hurt.
"It was a battle and until the end, we fought that battle. We lost a goal at the very last minute in added time, but all the players fought up until then very hard.
"Overall, I believe the result was a fair scoreline. We played a very good first half and maybe lacked a bit of quality, but overall, we are content with a draw.
"Three points were really close, but one point is also a good result. It's no surprise that Ireland came back to score an equaliser because the other results show that they know how to play to the end and get a result in their favour at the end of the game."