Adam Rooney’s double in what McInnes described as a “very dominant performance” secured Aberdeen’s seventh consecutive league victory and clean sheet.
The Irishman opened the scoring in the 36th minute after some poor defensive work from Motherwell, who did not get going as an attacking force until the final quarter.
The visitors got their second after Stephen McManus blocked Jonny Hayes’ shot on the line after Dan Twardzik had spilled Niall McGinn’s cross.
The ball seemed to hit the defender’s shoulder, but ref Willie Collum dished out his fourth penalty and third red card of 2015 and Rooney sent Twardzik the wrong way from the spot.
Celtic can narrow the gap to a point when they play at Kilmarnock tonight but the Dons have done everything demanded of them after getting the chance to go top on New Year’s Day.
McInnes said: “It was aimed at me after the game against St Johnstone that the players handled the pressure of going top of the league really well and I genuinely hadn’t thought about it. It was always just about the game.
“The players are honest enough just to have a real proper approach to the next challenge. We have come through the festive period with some strong performances and results. The pressure side of it hasn’t reared its head, it’s just something that we are enjoying.”
McInnes added: “The league table can change, a few weeks back we were behind Hamilton, Dundee United and Inverness. The challenge is coming from a lot of teams and that’s really encouraging.
“We are getting credit at the minute and I want to credit my players. Everybody is looking for a challenge and I understand that but there are others up there who deserve credit.
“We are just enjoying it and there is such a long way to go. The Christmas and New Year period does test your professionalism and focus and I think we have come through that brilliantly.
“If we start to look too far ahead that can question your focus and concentration and before you know it you are losing a game and getting a slap in the face because you have not approached it right.
“At the minute our approach is spot-on and we are giving ourselves a chance to win games.
“We are just looking for improvement this season and where that improvement takes us remains to be seen.”
Motherwell will appeal against the red card given to McManus. Manager Ian Baraclough said: “He has put his body on the line, he has not moved his arm towards the ball, it has hit him just below the shoulder. He couldn’t get out the way of it because it has been struck so well.”
MOTHERWELL: Twardzik, Watt, O’Brien, McManus, Reid, Ainsworth, Lasley, Kerr (Thomas 70), Law, Sutton (Erwin 70), Ojamaa.
ABERDEEN: Brown, Logan, Taylor, Reynolds, Considine, Jack, Pawlett (Smith 77), McGinn, Hayes, Rooney (Shankland 90), Goodwillie (Flood 86).
Ref: William Collum (Scotland).