Saints have allowed hooker Aaron Smith to join Super League rivals Hull KR on a month’s loan.
The 21-year-old has spent the last five weeks with York and scored two tries in their world record 144-0 win over West Wales Raiders at the weekend.
The Robins have signed the former England Under 18s representative- who has been at St Helens since the age of 11 - to cover at dummy half following injury to Shaun Lunt.
Smith was also part of the Saints Academy team which won the 2016 Championship.
Hull KR coach Tim Sheens said: “We’re thankful to St Helens for allowing Aaron to come across to us.
“He’s a bright young player with good speed and awareness out of dummy half who gives us specialist cover in that position until Shaun Lunt is available.
“Aaron trained with us for the first time today and we’ll monitor how he settles in over the rest of the week before deciding whether he’ll go into the side to face Wakefield on Sunday.”
Meanwhile, Josh Eaves is now on loan at Whitehaven alongside team-mate Liam Cooper on a week-by-week basis.