Italian Tebaldi features at scrum half with Hassler on the right wing as head coach Steve Tandy looks at the options available to him before the start of the season.
Tebaldi’s partnership with Dan Biggar is given time to grow with the start of the RaboDirect PRO12 just around the corner, the fly half one of a number of Welshmen in the starting line-up.
Ashley Beck, Eli Walker, Ryan Bevington, James King and Scott Baldwin also get the nod at the Liberty Stadium.
“It’s been a very long pre-season so it’s good to be able to go back to the Liberty and get back into action,” said Tandy.
“This game is an important part of our preparations for the new campaign and we want to get the performance right to allow us to start building some real momentum before we go to Treviso in a couple of weeks.
“We’ve gone with what we consider to be a strong team and there’ll be a first chance for supporters to see two of our new signings plus some of the exciting talent we’ve got coming through the ranks.”
In the pack, former Aberavon skipper Sam Williams gets a chance at lock, partnering King in the boiler house while Tom Smith starts in the back row as he aims to make an impression after missing the whole of last season through injury.
All of those involved on Saturday will be pushing for a starting spot against Treviso in the first PRO12 game with a final pre-season clash with Bath to follow next Friday.
British & Irish Lions Alun Wyn Jones, Adam Jones, Justin Tipuric , Richard Hibbard and Ian Evans are not involved as they step-up their pre-season preparations behind closed doors.
“Last season we saw our crowds rising and that had a massive impact on the boys,” said Tandy.
“We want to see that happening again this year, starting with Saturday afternoon rugby against English opposition.
“We are attempting to play a brand of rugby the local community can identify with and buy into. The signs have been very positive, with supporters appreciating the endeavour and effort they saw from the boys last season.
“It’s important we build on that this year.”
Ospreys team to play Worcester: (KO 3.00pm): 15 Richard Fussell 14 Jeff Hassler 13 Ben John 12 Ashley Beck 11 Eli Walker 10 Dan Biggar 9 Tito Tebaldi, 1 Ryan Bevington 2 Scott Baldwin 3 Joe Rees
4 Sam Williams 5 James King 6 Tom Smith 7 Sam Lewis 8 Joe Bearman.
Replacements: Matthew Dwyer, Marc Thomas, Dmitri Arhip, Ian Gough, Rhodri Hughes, Arthur Ellis, Dan Baker, Matthew Morgan, Jonathan Spratt, Tom Isaacs, Tom Grabham, Ross Jones.