Leg-spinner Warne, Test cricket's most successful bowler with 706 wickets, and McGrath, third in the all-time standings with 557 and the leading quick, will both call time on their careers in the five-day format after the fifth and final Ashes Test at the Sydney Cricket Ground starting next week.
The duo, who have each dismissed Inzamam five times apiece in Tests, will be looking to bow out by helping Australia complete the first 5-0 rout in an Ashes series for 85 years.
"Both are great players, great bowlers," Inzamam told.
"Without them Australia is definitely going to be a lot weaker and teams will now be much more confident about beating them. Both players always seem to perform when Australia win and it's no coincidence.
"Everybody in cricket will miss them, but more importantly I think Australia will miss them a great deal because they are big performers and take most of the team's wickets as we can see from the fact they have over 1,200 Test wickets between them.
"Every batsman will take a sigh of relief now they are gone."
And Inzamam predicted Australia would struggle without their two champion bowlers. "It's not good news for Australia as I can remember a couple of occasions when they didn't play and they found it very tough.
"When India toured there a couple of years back, they (Australia) drew the series and could have lost.
"That showed how much Australia rely on them. And the two matches England won in last year's Ashes was when McGrath didn't play. I know my own team will be a lot more confident of beating them now.
"Warne and McGrath are true greats and I could see that from how they took wickets in the sub-continent as well as in Australia and England. Some bowlers are good in their own conditions but cannot be as good in the sub-continent. But these two have proved themselves time and again."
Inzamam is set to lead Pakistan on their Test and one-day series tour of South Africa next month.
The squad includes Mohammad Asif, one of two Pakistan fast bowlers involved in a recent doping controversy. But Shoaib Akhtar, the other quick found guilty but then cleared of drugs offences, has been left out.
Akhtar, 31, and Asif, 24, tested positive for the steroid nandrolone in October and were banned for two years and a year respectively by a Pakistan Cricket Board (PCB) anti-doping commission in November.
But both bans were overturned by an appeal committee earlier this month.
"It was a shame Shoaib (Akhtar) couldn't make it," Inzamam added.
"But he hasn't played any cricket for three months and even before that he only played a few one-day matches in England, when he had waited about nine months to play cricket after injuries.
"So he will get his chance now to play some first-class cricket in Pakistan and hopefully he will prove himself and be ready to join us for the one-day series.
"Mohammed Asif has been bowling really well. I'm pleased to have him back with us."
The World Anti-Doping Agency, which deals with doping cases in international sport, has said it will challenge the overturning of the bans in the Court of Arbitration for Sports in Lausanne, Switzerland - a move supported by the International Cricket Council, the game's global governing body.