The Newcastle United manager has reportedly reached out to his predecessor to thank him for the squad he inherited on arriving at St James' Park last month, according to The i Paper.
Jaissle replaced Eddie Howe as Magpies boss in the summer, with Howe's five-year reign on Tyneside coming to an unexpected end in July following a pre-season defeat to Bristol City.
Howe had overseen an era that ended the club's long wait for a major trophy, but the exits of key figures including Sandro Tonali, Anthony Gordon, Kieran Trippier and Bruno Guimaraes eventually took their toll on his final months in charge.
The German, who signed a long-term contract to take over at St James' Park, has lost none of his early momentum since replacing Howe, guiding Newcastle to an unbeaten start across all competitions so far this season.
Newcastle have won one and drawn two of their opening three Premier League fixtures, while also progressing in the Carabao Cup with victories over Millwall and West Brom.
According to the report, Jaissle has been particularly struck by the physical condition of the squad he inherited, crediting the foundations laid during pre-season under Howe.
Jaissle is now turning his attention to Monday's trip to face Leeds United, with one significant selection call still to be made.
Summer signing Matias Fernandez-Pardo has made just two substitute appearances since his deadline-day arrival from Lille, but is edging closer to a first start.
"Yeah, he's getting closer," Jaissle told reporters. "I said that we need to be smart with his load management. Now he's getting more and more minutes.
"He has now almost a full training week to Leeds, that helps him a lot. I think it's the first time now since he arrived, and then we can make the decision on Sunday, maybe even on Monday."
The Belgium international arrived in a deal worth £51 million and is expected to add further attacking depth as Jaissle continues to shape his own identity at the club Howe left behind.