Andrew Flintoff's former England fast-bowling colleague James Anderson says it is a "smart move" for Lancashire to offer him a chance of a comeback.
Flintoff has held talks with his former county about a possible NatWest T20 Blast comeback at the age of 36.
The long-retired fans' favourite last played competitive cricket almost five years ago.
There was speculation he might return for Lancashire 2nd XI in a friendly against a representative team from the North Staffordshire and South Cheshire League at Leek on Tuesday.
Instead, he appeared at Headingley to join training with the first team squad before day three of their LV= County Championship match against Roses rivals Yorkshire.
His attendance was revealed on Yorkshire's official Twitter feed in a post which read: "Good morning from Headingley - and contrary to the forecasts, it's cloudy but dry. Surprise addition to Lancs squad warming up - @flintoff11."
Fellow Lancashire player Anderson, asked later if he thought it feasible for Flintoff to return to professional cricket, said: "If he's fit, and bowling well, then of course.
"With someone who has been out of the game so long, I guess the issue would be fitness - and getting up to match intensity."
There have been suggestions that Flintoff's return may not necessarily be in a playing role.
Anderson, speaking at England's press conference to preview their Royal London one-day international at Old Trafford, added: "I think it's quite a smart move from the coach's point of view - just to have him around.
"You can see the young guys trying to learn from him and talk to him about the game - to have him around is great, that sort of knowledge to tap into.
"But from a playing point of view, I think we'll just have to wait and see."
In his years away from cricket, Flintoff has explored other options - including one bout of professional boxing.
He represented England in 79 Tests, 141 one-day internationals and seven Twenty20 games. He also made 80 first-class appearances for the Red Rose, scoring 4,042 runs at 35.14 and taking 92 wickets at 29.16.
Flintoff's Lancashire Twenty20 record consists of 16 games, averaging 13.94 with the ball and 29.64 with the bat, with a high score of 93 against Derbyshire in 2009.