Thomas injured his knee and after having a scan on the injury was awaiting a second meeting with the specialist once the swelling had gone down.
"It looks like he will be out for at least 10 weeks through medial damage," explained coach Neil Kelly.
"It is a bitter blow for Adam, who was training well and hoping for a big season. Obviously it may be a better prognosis when the swelling goes down, but the main thing is to make sure Adam heals properly."
The departure of Dave Ingram was also something that Neil was saddened by.


"Dave has left on the most amiable of terms and of his own volition," said Kelly. "He did a smashing job with the reserves last year , and I wanted him to take on our under 18s this time out.
"That wasn't a demotion but a measure of what I thought about the job Dave could do, because the under 18s is an area where there is a massive challenge ahead.
"But Dave gave it his consideration and was extremely honest with me when stating that he didn't think he could give the commitment that was needed over the next two to three years to get this aspect of the club's future sorted out. He has a young family and this is a big job and he just laid his cards on the table.


"I am dreadfully disappointed to see him go, but hopefully we will keep in touch with regard to the future.
"But now that's an area where I have to assess the next steps.
"At the moment I have Paul Rowley as my assistant and Simon Knox is here too. I will not be rushing into appointing other coaches, as I have to assess what level of teams we will be running before we necessarily have to put more people in place.


"But I can only put on record my appreciation of the huge effort that Dave has put in during my time at the club and my thanks and best wishes go with him."


Ingram, who had been at the club for various spells since 1992 when he turned professional from Wigan St Patrick's, played 166 games between 1994 and 2002, in which he scored 100 tries and kicked three goals.

Following a final playing season with Chorley, Ingram returned to Hilton Park as assistant to Under-21s coach Mark Bailey and last season accepted the position of reserve team coach , guiding the side to the top of the table – only to bow out of the play-offs in the Final Eliminator.


Leigh chief executive Allan Rowley said: "Although losing Dave is a blow to our preparations for the new season, we wish him well and want to thank him for the excellent service he has given to Leigh Centurions."