Robbie Keane and Darron Gibson have been released from the Republic of Ireland squad ahead of the friendly against the USA.

The captain, who was left out of the starting 11 ahead of last night's 1-0 defeat to Scotland, was always a doubt for Tuesday's friendly after manager Martin O'Neill hinted he may be allowed return to LA Galaxy after the competitive tie in Glasgow.

Gibson, who was subsituted in 68th minute of the Euro 2016 qualifier last night, has returned to Everton with a "minor knock" to his knee. Those who did not play the full game last night trained today in Malahide United's Gannon Park.

Keane was adamant last night that he can still score goals at international level if he is used in the right way. The striker, who took his senior tally to 65 with a hat-trick against minnows Gibraltar last month, was left kicking his heels on the bench until 12 minutes from the end of the game last night.

Keane insisted afterwards he respected the manager's decision to leave him out — it was the first competitive game he had missed for his country when fit for 13 years — and field Shane Long as a lone striker with support from Jon Walters, but the LA Galaxy frontman hinted that if O'Neill wanted to persist with that system, it is not one to which he is best suited.

Keane played that role without much success in the 2-1 win away to Georgia and the 1-1 draw against Germany in Gelsenkirchen, only to be dropped last night.

"If the manager wants to play with one up front, I'm not Niall Quinn or I'm not Shane Long — they are better at that than I am," Keane said. "If you play two up front and you want to score goals, that's my game.

“Listen, I’d prefer to speak about the team rather than an individual, making a big deal out of someone else starting the game. “The manager made a decision and you have to respect that. Playing one up front doesn’t suit me, I think that’s fairly obvious. I’m 5’ 10”, so it’s not my game.”

Keane's personal anguish was exacerbated by a result which dented the Republic's qualification hopes and at the same time, boosted Scotland's chances of competing with them, world champions Germany and current Group D leaders Poland for the two automatic spots.

It was a game suited not to touch and flair players, but to those blessed with brawn and spirit, and Shaun Maloney’s decisive curling finish was a moment of rare quality on a night when the passion generated by a raucous crowd was transmitted on to the pitch.

It had been billed as an Old Firm-type clash and Keane, who played in two of those high-octane affairs during his loan spell at Celtic in 2010, admitted that was exactly how it turned out.

“Yes, it was, it was exactly the same as the Old Firm derby I played in when I came up here. No quality, just people trying to kick each other and stuff like that.

“The whole atmosphere, the build-up to the game — certainly, there wasn’t much quality out there, both teams trying to play.

“It was a scrappy affair and we knew that whoever was going to get the first goal was probably going to win the game, and that was the case.”

Victory was sealed 15 minutes from time by Maloney's inch-perfect curled finish, although Ireland very nearly snatched a point at the death, just as they had done in Germany last month, when Scotland defender Grant Hanley glanced substitute Robbie Brady's injury-time free-kick on to his own crossbar.

Keane said: “When you come away from home, the most important thing is if you don’t win the game, you don’t lose it. Unfortunately, we did.”

For all the despondency within the Irish camp after their first defeat of the campaign, there was a realisation too that there is a long way to go before the final standings are confirmed. Four of Ireland’s next five games will take place at the Aviva Stadium, the next of them in March against the Poles, who are now three points clear of the Republic, the Scots and the Germans on 10.

Keane and his team-mates now have four months to mull over the opening skirmishes in the battle to make it to France, and while disappointed at the result in Glasgow, the 34-year-old, a veteran of the 2002 World Cup and Euro 2012 finals, knows there will be further twists and turns along the way.

Keane said: “Listen, by no means is this over. We can’t get too down on ourselves. We are disappointed, of course we are, but overall if you look at the bigger picture, if you look at the points that we have, people probably expected us to have that around this point. But when you go away to Germany and get a point, you expect to come here and certainly get something out of the game. But we didn’t.”