Dave Connell's team drew with Slovenia in their opening First Phase game on Tuesday but that has been marked off due to the host nation fielded an ineligible player.
UEFA investigated the incident and have ruled that the fixture will be marked down in favour of Ireland winning 3-0, which means they are through to next year's Elite Phase qualifiers despite having one game still to play.
"We wouldn't have liked it to turn out that way but rules are rules. The girls are delighted and the pressure is off for the Russia game, but we're looking forward to that now," said Connell.
"We will prepare for that final game and hope to win it and top the group. We came here to win the group and it's something that we've done before in places like Serbia and Portugal.
"But we know that Russia are a good side. We played them at Under 17 level recently and we've looked at the DVDs of their game, so we know what to expect. But the girls are ready and looking to get another win."
Ireland were disappointed following their draw with Slovenia after having a late Evelyn Daly goal disallowed but they bounced back with a resounding 6-0 victory over Bulgaria and now face Russia on Sunday.
The winner of Sunday's game will top Group 10, but Connell's team have taken a huge step closer to next summer's finals tournament in Slovakia following UEFA's decision.
FIXTURES
Republic of Ireland WU19 3-0 Slovenia, Tuesday, September 15
Republic of Ireland WU19 6-0 Bulgaria, Thursday, September 17
Republic of Ireland WU19 v Russia, Sunday, September 20, KO 3.00pm, Gornja Radgona, Slovenia