MARTIN O'Neill has warned Sunderland winger James McClean he will not tolerate a repeat of the Twitter outburst that sparked controversy at the weekend.

McClean took to the social media website on Friday night to criticise Republic of Ireland manager Giovanni Trapattoni's decision not to use him during a 2-1 win in Kazakhstan.

The 23-year-old has courted controversy on Twitter before, most notably when he became embroiled in a public argument with Northern Ireland supporters after electing to play for the Republic.

O'Neill has stopped short of banning the midfielder from the website, but has spelled out in no uncertain terms that he is unwilling to accept a repeat of this week's events.

"If it happens to you once, there's an excuse," said the Sunderland boss. "If it happens to you twice, you have to consider it.

"If it's a third time around, then you've really got to ask yourself a few questions. He's stopped the tweeting now, although we don't know for how long.

"The best thing you can say is that he is learning. Or is he? It was kind of daft really.

"Somewhere along the way, he has to get into his head that the whole tweeting thing is public now. It's not as if he's talking to a couple of friends in private.

"He's speaking out publicly. He should realise that now because he's tweeted a number of things over a period of time that have got everybody up in arms."

O'Neill discussed the matter with McClean at the start of the week, and the pair spoke again in the wake of Tuesday's friendly with Oman, a game that saw the youngster cheered to the rafters as he made a 30-minute substitute appearance.

The Black Cats boss can understand his player's frustration, and can point to an example from his own past where he made a similar mistake.

However, given that McClean was still to make his senior Sunderland debut at the same stage of last season, he has urged the winger to display patience.

"James is a good player, a strong lad, but he has to think about it," he said. "This time last year, he wasn't in consideration for anything. It's been a great rise, now he just has to settle down, which I think he will.

"He wouldn't be the first player to be disappointed not to be in the team. I remember myself in my early days - I'd played for Nottingham Forest, so I thought I should be in the Northern Ireland side.

"But the manager at the time, Terry Neill, used some other players from lower leagues. I gave a stupid interview to some fella saying I should be in the team and it was kind of crazy. It came out badly. James can learn from these things."

While McClean at least experienced some international football this week, Adam Johnson was forced to drop out of the England squad after suffering a thigh injury.

The £10m winger was back in light training yesterday and should be available to make his home Premier League debut when Liverpool visit the Stadium of Light on Saturday evening.

"Adam's making progress," said O'Neill. "He was out training with Wes Brown and Phil Bardsley (yesterday) doing a little bit.

"It's too early to say whether he'll be available for Saturday, but he is making progress which is good. He feels the injury less and less every day, which is encouraging."

Johnson's injury meant there was no Sunderland representation in the senior England squad, but Connor Wickham posted a reminder of his talents with the winning goal as England Under-21s beat Norway on Monday night.

Wickham is expected to leave Wearside on loan in the next couple of weeks, with Burnley and Birmingham both understood to be interested.

"We'll see what happens in terms of loans," said O'Neill. "We have a number of players who can play at centre-forward at this minute.

"I've brought Steven (Fletcher) in, and have a bit of experience and back-up with Louis Saha. We've also got Fraizer (Campbell), so I'll have a look at it.

"We're in a strong position at the minute in terms of numbers, but I'd still have to be careful about the length of time that people might be going out on loan. We don't have that many choices, but we do have a choice there at the minute."