Portadown’s perfect start to the season was shut down by a single-goal defeat at Shamrock Park as unbeaten Cliftonville grabbed full points thanks to Jay Donnelly’s second-half strike.
Cliftonville produced the first opening of the match when David McDaid’s pass from the right arrived for Jay Donnelly off a dummy by Chris Curran but the shot was dragged wide.
Christian Stewart proved comfortable in possession and the teenager released Darren Murray down the left on 11 minutes.
The striker - who put an end to transfer speculation on Thursday night by opting to withdraw his request for a move - twisted and turned then delivered a cross but Gary Twigg failed to gain a clean connection.
Murray’s throw-in was then met by Keith O’Hara inside the area but the captain could not steer on target under pressure.
It proved Portadown’s most positive period of the first half, with Stewart and Ross Redman combing along the left to create problems for the visitors.
Goalkeeper David Miskelly - so sharp during Portadown’s opening two wins - was replaced by Billy Brennan on 43 minutes after picking up a knee injury.
Brennan was involved in the action moments after his introduction, scrambling back as Martin Donnelly’s delightful chip on the turn had the goalkeeper on the backfoot but the attempt bounced off the crossbar and Redman cleared the rebound.
Portadown produced a great opening when Redman’s free-kick was headed down at the back post by Garry Breen but Chris Ramsey’s shot on the run cleared the crossbar.
Cliftonville worked two promising chances after the interval, with McDaid and Martin Donnelly looking sharp but Portadown protecting the clean sheet.
James Knowles’ free-kick smashed off the crossbar, however, as the visitors grabbed control in the second half.
The game’s only goal arrived when George McMullan slipped a pass in behind the backline and Jay Donnelly displayed neat control to round Brennan and slot home.
Portadown’s response failed to spark into life and Brennan had to race off his line to prevent McDaid from increasing the gap before the final whistle.
PORTADOWN: David Miskelly, Chris Casement, Ross Redman, Keith O’Hara, Garry Breen, Peter McMahon, Darren Murray, Gary Twigg, Chris Ramsey, Robert Garrett, Christian Stewart. Subs: Billy Brennan (on for Miskelly, 43 mins), Mark McAllister (on for McMahon, 64 mins), Tim Mouncey (on for Stewart, 79 mins), Ken Oman, Jake Richardson.
CLIFTONVILLE: Peter Burke, Caoimhin Bonner, Johnny Flynn, James Knowles, Chris Curran (on for Garrett, 77 mins) , George McMullan, David McDaid, Martin Donnelly, Eamonn Seydak, Jay Donnelly, Tomas Cosgrove. Subs: Stephen Garrett, Mark Smyth, Ryan Catney, Jude Winchester (on for J.Donnelly, 92 mins), Martin Murray (on for M.Donnelly, 80 mins).
Referee: Tim Marshall.