St Helens have missed the chance to ensure that they finish the season at the top of the Super League table after losing by a single point to Huddersfield Giants, who have secured a top-four finish.
Two tries in just over two minutes from Tom Makinson and James Roby put the league leaders in a comfortable position midway through the first half.
However, Alex Walmsley was sent off just three minutes later for a late tackle on Luke Robinson, leaving St Helens a man short for over 50 minutes.
Huddersfield took the lead after the break, but St Helens drew level at 16-16 with 20 minutes to play, before Leroy Cudjoe edged Giants ahead with a drop goal.
St Helens pushed for a last-minute score which would have seen them finish at the top of the league, but they will have to wait for the rest of the weekend's results to see if they head into the playoffs as the top-ranked team.
Two tries inside the final 10 minutes from Jack Logan have given Hull FC a win over Leeds Rhinos in their final match of the season.
Tom Lineham put the hosts ahead early on, but Carl Ablett leveled just before the break for Leeds before a Kevin Sinfield drop goal edged the Rhinos ahead.
Danny McGuire and Ryan Hall extended the visitors' advantage early in the second half, but Logan led the late comeback to leave Leeds heading into the playoffs on a run of five defeats.
Widnes Vikings are in the playoffs for the first time, despite suffering a heavy defeat at the hands of Salford City Reds in their final game of the Super League season.
The hosts were in dominant form in the first half, scoring four tries in the opening 40 minutes to leave Widnes facing a big deficit.
Salford extended their lead further, with Junior Sau scoring two tries before Patrick Ah Van pulled one back late on for the visitors, who finish eighth in the table.
Results in full: Huddersfield Giants 17-16 St Helens, Hull FC 24-19 Leeds Rhinos, Salford City Reds 36-6 Widnes Vikings
