But, while he has calmed down, the Villa boss is still dampening down the expectations that are circling his side.
O'Neill should stop worrying. If there is a team now capable of breaking the monopoly of the Big Four, then his men look like the best candidates.
They have choked on the chance to overtake Arsenal in previous weeks but, this time, they grabbed it with both hands.
Goals from Gabby Agbonlahor (2), Ashley Young and a Kevin Davies own goal allowed Villa to put some daylight between themselves and the Gunners.
And with Arsene Wenger's side next up at Villa Park on Boxing Day, they have the chance to prove they are contenders and not the great pretenders.
But O'Neill said: "The other four teams have the experience, capabilities and bigger squads. They're capable of winning four games on the trot or taking 14 points from 15 and that would be hard work for us.
"We have a big, big month coming up. It'll be psychologically and physically demanding. Today was really difficult but we didn't expect it any other way.
"We have to keep Agbonlahor and Young fit and that might be asking a lot. But I wouldn't get too carried away with it."

They were hardly the confident words of a man with a place in next season's Champions League beckoning.
But O'Neill added: "Listen, I am enjoying this. In fact I'm going to my nephew's wedding in Manchester tonight and I'll be boasting."
O'Neill might well toast his gifted duo, Agbonlahor and Young, as well as the happy couple.
The two England youngsters were irresistible - too fast, tricky and deadly for Bolton to cope with.
O'Neill has put Young in the world-class category and, yesterday, the winger and his Villa sidekick dragged their team back into it.
Villa had not won on their own patch in four League games and Bolton took the lead in the 17th minute when Johan Elmander flicked in Davies' cross.
It should have been 2-0 when Gretar Steinsson's header rattled the Villa bar six minutes later.
But the hosts were back in it on 25 minutes when Agbonlahor pounced on an Andy O'Brien error.
Davies' 40th-minute own goal, from Gareth Barry's corner, then gave Villa the lead - before Bolton defender Gary Cahill handled in the box only for ref Lee Probert to wave away Villa protests.

O'Neill angrily threw his drinks bottle towards the dugout, too close to the fourth official for comfort.
He said: "It looked a penalty to me. But, to quote Shakespeare, all's well that ends well."
Agbonlahor bagged his second on 67 minutes when he drifted on to Young's cross and headed in.
And Villa were cruising when Young's deflected shot made it 4-1.
There was still time for Davies to score at the right end four minutes from time for a late consolation.
Trotters boss Gary Megson said: "It was a bad day at the office but, hopefully, it was one bad day."
Positive thinking from Megson. O'Neill should try it some time.
This article has 7 comments
well done villa, but now we need some consistency to keep us there. if we beat arsenal on boxing day I dont see why we cant go all the way.
up the villa.
By villain. Posted December 16 2008 at 8:19 PM.
we got a bit confident withe r win at sunderland we thought we could go in all guns blazing but the end result they deserved to win so well done villa
By luke . Posted December 14 2008 at 3:34 PM.
While it may be too early to be waxing lyrical about Villa's chances of sealing a 4th or even 3rd place, no one can deny the verve with which this team plays.
Yeah, keeping Agbonlahor and Ashley Young fit might be the key, but hey, we're enjoying our run!!!
GO VILLA!!!
By Bode O. Posted December 14 2008 at 2:04 PM.
Hansen and Lawrenson eat your hearts out. Technically we are top of the Prem as we have done it the traditional way - with good British management, mainly English players and spending little but wisely.
By Pongo Wearing. Posted December 14 2008 at 10:56 AM.
Good win and will be interesting to see who we get in the January transfer. The right buys could see us get that 4th spot or even above liverpool who i think will eventually finish third or 4th.
Hope we don't get Heskey, Crouch.
Would like to see Valencia, Roque, Steven Defour . These 3 signings would guarantee champions league football for next season.
By villa_2_Save_the_Premiership. Posted December 14 2008 at 12:24 AM.
I love football, i absolutley love football, what a result 4th place, are we the real deal i do think we are getting there a few more good games and points on the board between us and the gooners, and that 4th spot could be ours. UTV the only team in Birmingham. SOTC!!!!!
By Andy. Posted December 13 2008 at 9:52 PM.
All hail the King of Kings!!
By we are not worthy. Posted December 7 2008 at 5:12 PM.