Neil Warnock says Cardiff face a tougher weekend test after Southampton sacked Mark Hughes and appointed the little-known Ralph Hasenhuttl.
Hughes left Saints on Monday after winning only three of his 22 Premier League games in charge.
Hasenhuttl, the former RB Leipzig coach, takes charge of Southampton for the first time on Saturday, with even his first opponent Warnock admitting he knows little about the 51-year-old Austrian.
"I only know what I've read about him," Warnock said ahead of the huge relegation battle in the Welsh capital.
"He's done really well where he's been lower down. He's taken teams up, kept them up and done well in Europe.
"That's the league we're in now, it's open to everybody.
"Southampton have the filip of a new manager now, a spring in their step, and they'll all want to impress.
"They've also probably got the best squad in the bottom half of the division."
Hasenhuttl takes command with Saints stuck in the relegation zone after only one win all season and two points behind 16th-placed Cardiff.
But there was some comfort for Hasenhuttl in Wednesday's 3-1 defeat against Tottenham as Southampton created numerous scoring chances and might have considered themselves unlucky to lose.
"I only had one-and-a-half sessions when I first came here," said Warnock, dismissing the notion that Hasenhuttl has had too little time on the training ground ahead of his first game.
"You just get your points over, and from his point of view he's dealing with top-class players.
"He watched the game against Tottenham and Hugo Lloris got man of the match.
"Apart from some world-class saves, Southampton would have got something there."
Warnock spent Wednesday night in France running the rule over potential January transfer targets at the Ligue 1 game between Nantes and Marseille.
Nantes' 13-goal striker Emiliano Sala has emerged as one possible target, with Warnock admitting he is keen to strengthen his strike force next month.
"I went to watch a full-back, midfield player and a striker – all in the same game," Warnock said.
"We're out all the time now in Europe. South America is a little more difficult and certain leagues finish shortly as well.
"We've been looking as far afield as Russia as well, and we've looked at five or six strikers in the last few weeks.
"It's alright having scouts recommend targets but you've got to have someone that you know see them, as well.
"One game I went to – not the Nantes game – but another one I took in, I came back asking the question 'are they better than Ken Zohore?'
Warnock has been critical of Zohore in recent weeks, suggesting the Danish striker needs to show greater application on the training ground to get back in his plans.
"Ken is training now and I've had a word with him. He's got to get his finger out now because he's got all the attributes," he said.
"When I look at all these other strikers, the ones we're looking at, we're not looking at the right top end of the market.
"Ken's got it all in his locker really, it's such a shame."
