Maguire fired a clinical volley in off the underside of the bar
Motherwell were held to a draw by 10-man Aberdeen in a topsy-turvy match.
Jim O'Brien's first goal for 'Well, a deflected drive, handed them a deserved half-time lead but misfiring striker John Sutton should have made it more.
Sone Aluko went close for the Dons before Chris Maguire drew Jimmy Calderwood's side level with a volley.
Andrew Considine was sent off for two bookings and Jamie Langfield made a great late save to deny Brian McLean as the visitors held on.
Aberdeen rarely threatened before Maguire's smart strike, but the point leaves them virtually assured of a top-six place as they sit four points ahead of Motherwell and Hibernian.
Lee Miller returned after a month out with a hamstring injury but, with Sone Aluko on the bench, there was little service from Aberdeen's five-man midfield before the interval.
The home side started strongly and Steven McGarry had a 30-yard volley saved before O'Brien cut inside and played one-twos with Paul Quinn and David Clarkson before finding the net with a powerful low drive, which went in off Scott Severin.
Motherwell continued to dominate and gave the Aberdeen defence an uneasy time with some sharp, short passing in the visitors' half.
Sutton had a great chance to put Motherwell two up but he sliced the ball 12 yards out after Clarkson's square ball bobbled on the uneven surface.
Langfield held Clarkson's attempted chip and the striker had another shot deflected wide after good movement to meet Brian McLean's free-kick.
Quinn, standing in as skipper in the absence of the injured Steven Craigan, then headed O'Brien's corner wide from eight yards after escaping his marker.
Aluko came on for defender Lee Mair at half-time as Aberdeen moved to a 4-4-2 and they immediately showed more attacking threat.
Motherwell found their feet after a slow opening to the half and Clarkson volleyed inches wide from 18 yards after Sutton nodded down O'Brien's cross.
Efforts from McLean and Clarkson sailed not far over and Langfield pushed Stevie Hammell's dangerous cross over his own crossbar.
Smith palmed wide Aluko's powerful strike and the Dons were soon level.
Miller flicked on Severin's long throw and Maguire turned and blasted it in off the bar from six yards.
Aberdeen's celebrations were soon tempered by a red card for Considine, who clumsily bundled over Clarkson on the touchline less than 15 minutes after being booked for dissent.
Motherwell pushed forward and Sutton's 20-yard drive deflected agonisingly wide off team-mate Stephen Hughes.
However, although Sutton had a decent penalty claim rejected when he appeared to be pulled by Charlie Mulgrew, Mark McGhee's team failed to exert any more pressure until injury time.
O'Brien set up two good chances but Langfield brilliantly pushed wide a header from McLean and Hughes nodded wide from 12 yards.
Motherwell manager Mark McGhee: "I think it's a point gained. Maybe on the balance of the game we should have turned it into a victory.
"We've played well and with good energy at this stage of the season, which bodes well for the last seven games.
"I think with two games to play we're still in the mix for a top-six spot.
"We've Rangers away and St Mirren at home and I think four points will give us that top-six finish.
"If we make that we'll still have a chance of making the top four judging by the way the points have gone.
"We know we still have some work to do but given the problems we had in December to be on the cusp of the top-six is still not a bad achievement."
Aberdeen manager Jimmy Calderwood: "I think the way we played meant Motherwell were in the ascendancy and caused us problems.
"With 10 men at a very difficult venue it's a point gained. It wasn't a game for the purists.
"We got a wonderful goal from Chris McGuire, we thought we'd take confidence from that, and I thought we'd go on to win the game.
"But then Andy Considine got sent off, and that made it very, very difficult.
"Jamie Langfield pulled off a great save at the end. He's been wonderful for us all season."
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