Saints' 3-1 triumph at Selhurst Park on Boxing Day proved the catalyst for change in south London.
Neil Warnock was promptly sacked by the struggling Eagles, who head into Saturday's FA Cup fourth-round tie at St Mary's riding the crest of a wave.
The appointment of Pardew has brought with it an impressive change in fortunes at Palace, with their former player overseeing three successive wins in all competitions.
"They have a spirit in the team, the confidence and they have had a great start (under Pardew)," Koeman said of Palace.
"The first win (against Dover) was normally an easy FA Cup round for them, but the first victory in the Premier League against Tottenham Hotspur gave everybody confidence.
"At the moment they are more difficult to beat than over Christmas on Boxing Day.
"They have new players and a new manager and that always means some changes in tactics or organisation in the team and I think the manager is more happy than he was before, and that's important."
Palace sit 13th in the standings ahead of Pardew's trip to the club he led to the Johnstone's Paint Trophy in 2010.
Jose Fonte started that 4-1 defeat of Carlisle and will captain Saints this weekend as they continue their campaign to reach Wembley for the first time since then.
"I am lucky," Koeman said
"I don't have a lot of numbers of players to think about to make changes.
"The players who wasn't available in the last week are still not available for this weekend.
"That means we have 17 or 18 players and of that 17 or 18 players we have already five or six Under-21 players.
"There is no time and no reason to think about making changes and we will put out the strongest team we can."
Toby Alderweireld, Victor Wanyama and Morgan Schneiderlin are among those unavailable, joining long-term absentees Sam Gallagher and Jay Rodriguez in the treatment room.
International commitments mean Sadio Mane, Emmanuel Mayuka and Maya Yoshida further reduce numbers, but Saints do have the momentum of a eight-match unbeaten run on their side and a sell-out St Mary's crowd.
Pardew insists he did not dismiss the FA Cup during his time in charge at Newcastle - despite a dismal record in the competition throughout his tenure at St James' Park.
The 53-year-old takes his Palace side to another former employer having already matched his win record at Newcastle following victory over Dover in his first game in charge.
With cup humiliation coming with defeat at Stevenage in 2010 and Brighton knocking out the Magpies twice in successive years, many could point an accusatory finger at Pardew for his approach to the competition.
A 2-1 success against Blackburn in 2012 was his only victory in the competition in a four-year spell on Tyneside, which came to an end when he left in December to fill the managerial vacancy at Selhurst Park.
But Pardew maintains he always gave his best and understood what delivering silverware to a trophy-starved Newcastle fan-base would have meant to the city.
"That is the perception but it wasn't the case," he said when asked if he took the competition lightly in the past.
"It was just at times we were unlucky in terms with selection of teams
We had a couple of bad results in that competition and, of course, the way it is with cups and their longing for a trophy after all these years, the hurt at going out was magnified each time.
"Unfortunately I have to accept that but I can assure you we didn't plan for it
I have always done the same with cups.
"I have tried to make sure the team is competitive and sometimes you do have to look within your squad and give people the opportunity, as we did at Dover
Then hopefully you find out things about players, sometimes for the good and sometimes for the not."
Pardew has a fully fit squad for the trip.
Marouane Chamakh is now available having not played since December 13 due to a hamstring injury and Pardew has given the Morocco striker every chance of being involved at St Mary's.
The only two absentees are Yannick Bolasie and captain Mile Jedinak, both of whom are away on international duty.
Source : PA
Source: PA