After going through a lean spell, Alker got his career back on track with a victory at the Utah Championship last year and just missed out on claiming a card for this season's PGA Tour.
Alker nearly won the Cleveland Open outright but he bogeyed the last two holes of his final round at the Lakewood Country Club for a six-under 65 and van der Walt made a pair of birdies as he shot a 66 in his final round. The pair finished at 14-under for the week before Alker finally got the job done for his fourth Web.com Tour win.
Alker began the week in 102nd place on the Web.com Tour's order of merit but jumped to 12th with $147,000 in earnings for the year and he could secure a PGA Tour card for next season providing he can remain in the top 25.
The showdown with van der Walt also equalled the longest playoff in a PGA Tour-sanctioned event. In 1949 at the Motor City Open, Cary Middlecoff and Lloyd Mangrum slugged it out for 11 holes but agreed to call it a day when they couldn't be separated and were declared co-winners.
Meanwhile, on the PGA Tour, Kiwis Danny Lee and Tim Wilkinson both recorded a disappointing three-over 73 during the final round the St Jude Classic in Memphis today as they finished in a share of 32nd.
American Ben Crane won the tournament at 10-under despite shooting 73 in his fourth round.
At the Lanhai Open in Shanghai, Waikato's Mathew Perry finished in a share of 10th at three-under yesterday as he continued his solid season on the PGA Tour China.
The Melbourne-based professional shot a seven-under 65 during his final round to rocket up the leaderboard as Australian David McKenzie cruised to an emphatic win as he finished the week at 16-under, five strokes ahead of his nearest rival.
Kiwi Mark Brown finished in a share of 26th at even-par at the Lan Hai International Golf Club's Links Course, while former New Zealand Open champion Mahal Pearce ended the tournament in a tie for 42nd at four-over.
Auckland's Ryan Fox defended his Tahiti Open title with a one-stroke win over fellow Kiwi Kieran Muir yesterday as he finished the event at 20-under with a three-under 69 in his final round.