Manchester City secured their first major domestic trophy of the season with a commanding 2-0 victory over Arsenal in the English League Cup final on Sunday.
"It's an unbelievable feeling to win a final and to beat this team. We know how good they are," City goalscorer O'Reilly told Sky Sports. "We need to build on it now, it'll give us momentum."
The win marked City manager Pep Guardiola's 16th major trophy as manager and a record fifth League Cup. Including his time at Barcelona and Bayern Munich, Guardiola has now won 34 career titles.
"I'm really pleased because I know the opponent we played. Mikel created a team that is almost unbeatable," Guardiola said. "Every time you win a title it looks more difficult than in the past. It is really difficult for many reasons."
This was Guardiola's second victory over his former assistant Mikel Arteta in a major final in recent years, dashing Arsenal's hopes of ending their long drought without a league title.
Arsenal remains favourite to be crowned Premier League champions this season for the first time since 2004, given their lead at the top of the table. However, second-place City have a game in hand and the teams still meet at the Etihad Stadium.
"I'm very sad. It is a very hard one to take, especially for our players and our supporters because we know how much it means to them," Arteta said. "We will manage that energy in the right way and we have to go through that pain and disappointment."
City's win also ended Arsenal's bid for an unprecedented quadruple of major trophies by an English team.
21-Year-Old O'Reilly the Unlikely Hero
The 21-year-old O'Reilly, who came through City's academy, scored both goals from left back.
He took advantage of Arsenal goalkeeper Kepa Arrizabalaga's fumble to head City in front on the hour. And he headed in a second four minutes later to effectively seal the victory.
"My whole family came down today to watch. I know they'll be buzzing and I can't wait to see them," O'Reilly said.
Arteta said he had no regrets about selecting Kepa, who had played in previous rounds, rather than first-choice David Raya.
Premier League Crisis Deepens for Tottenham
Tottenham's Premier League survival fight was plunged deeper into crisis with a 3-0 loss to Nottingham Forest at the Tottenham Hotspur Stadium.
The relegation six-pointer left Spurs one place and one point above the drop zone and raised further questions about the future of coach Igor Tudor.
"The season is tough, especially in this moment. Another very bad result for us," Tottenham captain Cristian Romero said. "The situation is tough, but most important thing is play every game like a final now."
Fellow relegation-fighting Forest climbed above Spurs to 16th in the standings.
Tottenham, one of English soccer's most iconic teams, is still without a win in the top flight in 2026. Their last win came on December 28, and they have lost six of their last seven games.
Igor Jesus' header just before halftime gave Forest the lead. Morgan Gibbs-White added a second just after the hour mark, and Taiwo Awoniyi completed the scoring in the 87th minute.
Tudor was hired last month to try to turn Spurs' season around but has lost five of his seven games in charge.