Hearts manager Jim Jefferies insists clubs can challenge the Old Firm in the future, but only if the current downward financial trend continues.However, Jefferies believes, if Rangers attract new ownership and investment this summer, the gap could widen again.
"Rangers and Celtic maybe don't spend the money that they spent 10 years ago, but they are still spending more than anybody else," said Jefferies.
"The fact is, as this season has shown, they are a little bit closer."
Hibernian had threatened to split the Old Firm and could have moved above second-top Celtic had they defeated leaders Rangers on Sunday and followed it up with a victory over St Johnstone on Wednesday.
If Rangers are taken over in the summer and pots of money are invested in top players then it all kicks off again
Hearts manager Jim Jefferies
But Hearts' Edinburgh rivals were beaten 3-0 at Ibrox and then slumped to a 5-1 shock hammering in Perth.
Rangers announced half-year profits of more than £13m on Wednesday, thanks mainly to Champions League involvement, 24 hours after Celtic revealed interim results for the six months to the end of 2009 showing a 22.8% decrease in turnover to £36.11m.
But Jefferies, who returned to Hearts in January for his second spell in charge of a Tynecastle club who are themselves running up a debt of around £30m, believes both sides of the Old Firm will remain the net spenders in Scotland.
"There is the possibility that if things continue as they are then there is a chance they could be challenged," said Jefferies.
"But if Rangers are taken over in the summer and pots of money are invested in top players then it all kicks off again.
MY SPORT: DEBATE
Give your reaction to challenging the Old Firm
"I also think Celtic are only going to get better.
"Tony Mowbray has brought in a number of new players who are going to take time to settle in.
"They are a decent squad and I'm sure they will improve."
Hearts host Hamilton in the Scottish Premier League on Saturday, with Jefferies' side currently in sixth place.
Source: BBC Sport