Manager Mark Warburton believes Rangers deserved their Scottish Cup semi-final win but reiterated his view that a gap remains between his side and Celtic.
Warburton, experiencing his first Old Firm derby, was delighted as Rangers prevailed on penalties at Hampden.
However, he was quick to stress that Sunday's result could not be used as a gauge for next season.
"Again, there's a gap, don't be fooled, but the better team won on the day," said Warburton.
"Celtic are a team packed with international players and we've got to work hard to close the gap. What today showed is that the gap is nowhere near as big as certain people have made out.
"We've made dramatic strides but we've got to keep moving forward. Rangers can't afford to stand still.
"We can't be satisfied going into next season being second, third or fourth. We've got to be highly competitive."
Tom Rogic levelled in the second period of extra time to make it 2-2, only for the Celtic substitute to miss the vital spot-kick in the shootout.
Kenny Miller had given Warburton's side a first-half lead, with Erik Sviatchenko equalising five minutes after the break and Barrie McKay firing in an unstoppable shot early in extra time to re-establish Rangers' lead.
Rangers, who won the Challenge Cup at Hampden last weekend, will face Celtic in the Premiership next season, having wrapped up the Championship title with four matches to spare.
Before Warburton considers upsetting Celtic's recent top-flight dominance he has a final with league rivals Hibernian to look forward to on 21 May.
The Easter Road side also went through on penalties, following a drab 0-0 draw with Dundee United on Saturday.
"That will be a tough test," said the former Brentford boss. "Hibs have got a strong squad and they'll be keen to end the season on a high."
'European football would need bigger squad'
A cup final victory would also bring European football back to Ibrox and Warburton admitted: "That would impact our recruitment.
"If we win the final we'd have to add one or two more players in terms of depth to the squad. That type of competition has to go on."
With top-scorer Martyn Waghorn and winger Harry Forrester injured and Michael O'Halloran cup-tied, Warburton chose to name just five substitutes at Hampden.
"You saw we were down to the bare numbers today so all credit to them," he enthused.
"No one hid from the occasion, all over the park they were superb, so I'm delighted for the squad."