Championship strugglers Rotherham United suffered an FA Cup exit at the hands of League One side Oxford United.
Ryan Taylor's first-half strike was chalked off with a Danny Ward goal, before Phil Edwards and Kane Hemmings put the visitors in charge.
Tom Adeyemi's late goal was little consolation for the Millers.
Rotherham were forced into a late team change, when Peter Odemwingie was injured in the warm-up and had to be replaced by Dexter Blackstock.
Oxford included three former Millers in their squad, Maguire, Taylor and Joe Skarz.
The hosts had a glorious chance to settle their nerves in the opening minutes, as Danny Ward raced clear.
But with just goalkeeper Simon Eastwood to beat, Ward - linked with a January move to Sheffield Wednesday - dragged his shot wide.
At the other end, Marvin Johnson was allowed space to drive forward but hammered his shot over the crossbar.
How Maguire did not score inside the opening 10 minutes will remain a mystery. The striker broke clear down the middle, but with just Price in his way he stroked his shot beyond the keeper's right-hand post.
Left-back Joe Mattock then had to race back to deny Alex MacDonald after a swift break from Taylor.
It was an open contest, with little to choose between two teams divided by just a dozen places in the league pyramid.
Blackstock was next to spurn a good opening. The ball broke to the Rotherham striker, free inside the box, only for Curtis Nelson to appear from nowhere to nip in and clear the danger.
Oxford should have been in front before half-time, when Kirk Broadfoot fouled Taylor inside the box.
But Maguire saw his penalty well saved by Price, low down to his left, to the relief of the Millers supporters behind that goal.
Ward saw his effort deflected wide, but the Millers were too open at the back and were punished in the 42nd minute.
Maguire picked up the ball in acres of space in midfield, and as Rotherham scampered back to close the gaps, Oxford picked them off as Taylor fired home against his former club.
Even then, the hosts could have score before the break, but Tom Adeyemi's header was well saved by Eastwood.
Ward levelled the game on 51 minutes, and what a beauty. He showed strength to hold off the defender, before blasting the ball beyond a stranded Eastwood.
Blackstock was replaced by youngster Jerry Yates, as Millers boss Paul Warne looked for fresh legs up front on 53 minutes.
And the hosts upped the tempo as they pushed for a second goal.
Ward fired narrowly over with a rocket of an effort, Will Vaulks hit the post, before seeing another long-range shot deflected off Ward but Eastwood safely collected.
Rotherham's No 9 was having a far better second half, finding space and driving at defenders. One tricky run deserved a goal, evading three challenges, but Ward could not beat Eastwood.
And the hosts were punished for their missed chances, when Phil Edwards was left unmarked at a corner and Price was unable to keep his header out with 10 minutes to go.
Darnell Fisher's right-wing cross was side-footed wide by Ward, but it was Oxford who netted as substitute Kane Hemmings headed home.
There was still time for Adeyemi to head in a response from Rotherham, but they were unable to find an equaliser in four minutes of stoppage time.
Hemmings tapped wide but a fourth away goal would have been harsh on the Millers, who fell at the first hurdle of this year's FA Cup.