Mark McCall expects fans to again boo Billy Vunipola following the Saracens and England forward's official warning from the Rugby Football Union for a homophobic Instagram comment.

Rugby director McCall confirmed Vunipola will start Saturday's Champions Cup semi-final against Munster at the Ricoh Arena, then said the number eight must handle whatever flak comes his way.

The 41-cap back-rower has been warned by both club and country after a social media post last week that read "man was made for woman to procreate that was the goal no?"

The England star had liked a social media post from Australia's Israel Folau, that stated "hell awaits" for "homosexuals", and was subsequently booed by supporters during Saracens' 23-21 Premiership defeat at Bristol on Saturday.

Asked if he hopes fans will not boo Vunipola again, McCall said: "That's not something we can control to be honest. Whatever happens will happen.

"He has got to deal with that, and we've got to deal with that as a group. It's probably better to expect it to happen, and then wait and see."

Wallabies full-back Folau's career is in tatters after he was sacked by the Australian Rugby Union (ARU) for his controversial Instagram post.

The devout Christian has pledged to accept his fate, while England star Vunipola has been warned about his future conduct after liking Folau's post.

Asked if McCall was concerned for Vunipola's mental state, McCall continued: "No. Billy's sensitive, but I think he's also strong.

Billy Vunipola during Saracens' clash with Bristol  

"He's also got a group he's been with for a long time now, and a group who support their team-mates.

"They get behind each other from a rugby point of view, and that's what we'll do for this weekend."

Escaping a fine or a ban leaves Vunipola available for England's four warm-up Tests ahead of autumn's World Cup.

The RFU statement read: "Following a meeting between the RFU and Billy Vunipola, the Saracens forward has been issued with a formal warning under RFU rule 5.12 for conduct prejudicial to the interests of the union or the game.

"The warning will be retained on his disciplinary record for a period of five years and may be taken into account in future disciplinary proceedings.

"During the meeting the player expressed genuine regret at his public comments and understood that he had caused hurt and offence as a result of his actions.

"He has been reminded of his responsibilities as an England player and as an ambassador for the game, which values inclusivity and respect."

Saracens also issued Vunipola a formal warning after their own investigation, admitting the England star was guilty of a "serious error of judgement".

Vunipola himself insisted his "intention was never to cause suffering", though stopped short of offering an apology.