Sharjah joined hurdling greats Hurricane Fly and Istabraq by landing his fourth Matheson Hurdle at Leopardstown.
Willie Mullins' talented performer toughed it out in the Grade 1 to continue his impressive record.
The eight-year-old swept down the outside and quickened to challenge Zanahiyr as they bypassed the final flight.
Asked for his winning effort by Patrick Mullins, Sharjah pressed on to defeat his battling rival by a neck.
"That wasn't good for the heart!" the trainer said.
"Patrick said he wasn't as sharp as he was other years.
"With the last hurdle missing, he got pushed out on to yesterday's ground and that probably just blunted his speed in the last furlong, but he still managed to get the job done. It was a terrific race.
"He's been spectacular. It's fantastic for Patrick and Rich and Sussanah [Ricci]. Rich likes Patrick riding him and he's been a special horse for that partnership.
"We might miss the Dublin Racing Festival [Irish Champion Hurdle] and go straight to Cheltenham. It might be the thing to do as that race doesn't seem to work for him."
Patrick Mullins, the rider of Sharjah – who for the first time started favourite for the race – said he could try and make it five in 2022.
"We went a good strong gallop all the way," he added.
"I'd like to think we won despite having a lot of things going wrong, I think Zanahiyr had the perfect run and we didn't so I think our fella deserved the win.
"This wasn't a vintage performance on ratings but things went wrong and he still won and he's only eight.
"I can't see why he couldn't come back and do it next year. "
Coral trimmed Sharjah's price to 8-1 (from 10-1) for the 2022 Champion Hurdle.
"Having finished second in two Champion Hurdles, Sharjah clearly cannot be ignored as a contender for the big one in March, although the odds suggest he will have it all to do to dethrone Honeysuckle at Cheltenham," said the firm's David Stevens.
