The strong-running centre, who played for Samoa at last year's Rugby World Cup, linked up with Connacht in November 2005 and had quite a successful stint with the westerners.
Dax are currently ninth in the French Championship table, with Williams having scored a try in their 27-17 win over Bayonne last weekend.
The Auckland man has formed a potent midfield partnership with Argentinian international Federico Martin Aramburu and will put friendship to one side for Friday's Pool 1 encounter with Connacht.
"I'm excited about playing Connacht. I still know a lot of people at the club and am looking forward to welcoming my old team to Dax and having a good hard game and meeting up with some old friends," he told the Galway Independent.
"The support Dax have at home is really good, we often have brass bands playing in the crowd and there's a lot of singing and dancing.
"There's a real buzz in French rugby following on from the World Cup, so it's a good time to be playing here.
"It's getting better all the time and I'm getting lessons but it's a great place to play rugby and the weather here in October is still fantastic."
Williams and his team-mates will have sat up and taken notice of Connacht's nuggety performance in beating Magners League champions Leinster in Galway last Sunday.
And while Connacht have their own master tactician in Michael Bradley, Dax have former France number 8 Thomas Lievremont installed as their coach this season - an appointment which Williams welcomed.
"Thomas has 30 or 40 odd caps for France. He knows what he's talking about and he's a good communicator," the 28-year-old explained.
"He played with us last year and this is his first year coaching, so I know him quite well.
"I think when you're just starting out coaching you're still very much in touch with how the modern game is played and we're benefiting from it."