The Lions had to overcome a fantastic comeback by the Rebels, who scored three second-half tries to turn a 7-24 half-time deficit into a 32-27 lead.
But replacement flank Jaco Kriel then charged down the blindside to score an equalising try, which Jantjies converted from the touchline to give the Lions the lead, the young flyhalf then kicking a penalty on the final hooter to stretch the winning margin to five points.
The Lions, who have an interim coaching staff due to the suspension of former All Black mentor John Mitchell, played with enormous confidence and freedom in the first half as they ran in three tries and Jantjies kicked a penalty to give them a 24-0 lead after 36 minutes.
“We had a disappointing first 15/20 minutes, making simple, fundamental errors in good field positions, that gave the Lions lots of possession and, to their credit, they turned that into points,” Rebels coach Damian Hill told a news conference after the game.
The home side made a great start when right wing Lionel Mapoe stepped inside and sent outside centre Waylon Murray over for the opening try after just two minutes.
Nine minutes later, Mapoe and Murray again combined well down the right, the Lions then quickly swinging the ball to the left, where outstanding flanker Derick Minnie barged his way over the tryline.
The Rebels tried to stretch the Lions with clever attacking play, but they struggled to get on the front foot against an aggressive defence, and the Lions also ruled the breakdowns in the first half. The Australians went off their feet at a ruck in the 25th minute, allowing Jantjies to kick a penalty (17-0), and Minnie then read the situation perfectly as he burst from a rolling maul through a big gap in the defence to score his second try.
The Rebels finally had some points on the board on the half-time hooter as they protected the ball well in a rolling maul, hooker Ged Robinson emerging with the try, which was converted by fullback Julian Huxley.
Having dominated the opening 40 minutes, it was a case of losing focus in the second half for the Lions, who also lost their discipline at the breakdown and conceded a string of penalties to give the Rebels momentum and territory.
“There was a lack of concentration in the second half, especially defensively, with guys not manning up in the one-on-one tackles,” Lions captain Josh Strauss said. “If we can keep concentrating for 80 minutes and play like we did in the first 40 minutes, then we’ll be a very dangerous side. We’re still playing for pride and each other.”
Lock Hugh Pyle scored two tries in three minutes for the Rebels, crossing over in the 47th and 50th minutes.
His first try came after the visitors kept the ball in the forwards, tighthead prop Jono Owen also carrying strongly, while his second came after wing Mark Gerrard had sped back into the Lions’ half from the kick-off, scrumhalf Nick Phipps was up in support and Pyle was able to take advantage of a big overlap on the right.
Huxley converted Pyle’s first try and then brought the Rebels to within two points in the 58th minute as he kicked a penalty after the Lions failed to roll away in the ruck.
Jantjies replied with a penalty which stretched the Lions lead to 27-22, but then became the villain of the piece as his clearance kick was charged down by flyhalf Jimmy Hilgendorf to give the Rebels an equalising try which was confirmed by Television Match Official Johann Meuwesen.
Huxley converted to give the Rebels a 29-27 lead, before adding a penalty which stretched the lead to 32-27.
“There’s a good spirit and camaraderie in the group and we’ve consistently shown that when we’re down, we find a way back. But too often we let ourselves down first and we need to find a way to be better as a team, to be able to put pressure on the opposition from the start,” experienced Rebels captain Stirling Mortlock said.
But Lions scrumhalf Michael Bondesio then caught the Rebels defence napping with a pop-pass down the blindside to Kriel, who powered through the cover defence to score in the corner.
The 21-year-old Jantjies kept his calm to kick the conversion and give the crowd a happy ending to the Lions’ last home game of the season, and perhaps their last in SuperRugby as they are slated for relegation next year to make room for the Southern Kings.
Lions – Tries: Waylon Murray, Derick Minnie (2), Jaco Kriel. Conversions: Elton Jantjies (4). Penalties: Jantjies (3).
Melbourne Rebels – Tries: Ged Robinson, Hugh Pyle (2), Jimmy Hilgendorf. Conversions: Julian Huxley (3). Penalties: Huxley (2).