Odds-on favourite Altior claimed a record-equalling 18th consecutive success over jumps thanks to a nervy win in the Queen Mother Champion Chase at the Cheltenham Festival.
Nicky Henderson's superstar (4-11) was far from dominant but dug deep to win by one-and-three-quarter lengths.
In the Cross Country Chase, a powerful display by Grand National winner Tiger Roll saw him take the race.
It gave trainer Gordon Elliott his first win of the week.
The nine-year-old, ridden by Keith Donoghue, romped clear for a 22-length victory - his fourth Festival success.
He remains a strong favourite to retain his Aintree crown next month.
- 'Worst decision in 25 years' - McCoy criticises BHA's jockey suspensions
- Paisley Park aims for Festival success - Thursday's preview
Altior digs deep
Altior came to the Festival on the back of an unbeaten run dating from October 2015 and covering five hurdle races and 12 steeplechases.
The victory means he is now level with four-time long-distance hurdling champion Big Buck's, whose winning record spanned 48 months from January 2009.
While Saint Calvados set off at a fair pace, Altior and jockey Nico de Boinville stayed close with both horses pulling clear early on.
Altior had a slight mistake at the water jump - the seventh of 13 fences - but seemed to settle down after that.
- Cheltenham Festival day three preview podcast
- 'The lady on the counter... her face dropped' - Cheltenham punter wins £182,567 from £2 bet
However, the rest of the field was never too far away and turning from home with two fences still remaining, the title was still up for grabs.
Politologue and Sceau Royal loomed large, and after two less than fluid jumps at the final fences, it looked like Altior's unbeaten record could come to an end on the big stage.
But the nine-year-old showed his class to push to the line and land the race for the second year in a row, making it four consecutive wins at the Festival and giving Henderson a record-equalling sixth win in the race.
'For me it was hell'
There were some anxious moments during the race for Henderson before he could celebrate his 63rd Festival win.
"He's a better horse on better ground, we've always said that, and he did get headed," he said afterwards.
"But he very quickly found all that was needed. He's hugely talented, but very brave as well.
"He had to have a little fight there today, but he made it exciting for everybody - including myself.
"It was a cracking good race, but for me it was hell."
De Boinville added: "What an absolute monster and aren't we lucky to be in an age where he's here.
"We should just celebrate him. He's a phenomenal athlete - he doesn't know how to lose."
It was a second win of the day for jockey and trainer after William Henry edged out fellow 28-1 chance Wicklow Brave in the Coral Cup.
'A magnificent champion' - analysis
by BBC horse racing correspondent Cornelius Lysaght
To be a champion, you don't necessarily have to ooze the sort of wide-margin flamboyance that Altior's charismatic former stablemate Sprinter Sacre, a two-time winner of this, used to ooze.
To steal a cliche loved at racecourses from Cheltenham to Chelmsford, some horses 'only do enough', and that was what happened here as Altior, who didn't look to be enjoying the rain-softened going, carved out a special place in Festival history.
The winning streak looked in severe jeopardy at the final fence, but he demonstrated champion class aplenty by, as it were, rolling up his sleeves, gritting his teeth and seeing them off.
Tiger Roll roars again
In contrast to Altior, Tiger Roll, who went off as 5-4 favourite, made it look easy around the cross-country fences with Josies Orders (15-2) second, in front of last year's runner-up Urgent De Gregaine (17-2).
After his victory in the corresponding race 12 months ago, the horse, owned by airline boss Michael O'Leary, went to Aintree and won the biggest race of them all.
He is now as low as 6-1 favourite to become the first dual National winner since Red Rum.
Tiger Roll's success halted what has been a disappointing Festival for Elliott, who had four favourites beaten in the first two days.
"Everyone knows it's been a rough week," he said. "Horses haven't been running up to par, a few of them haven't been good enough and things haven't been working.
"We're lucky enough that we've got a good bunch of owners and a good bunch of horses. We'll keep smiling and keep kicking.
"He's our first winner of the week and I won't forget him. I'm very lucky to have him."