You are not permitted to download, save or email this image. Visit image gallery to purchase the image.
Both pairs of teams have met on three occasions through the qualifying rounds. Top qualifier Valley lost to Maheno 19-0 in the first round before Valley won the next two rounds 38-19 and 42-12.
Old Boys lost its first round encounter with Excelsior 17-7, but Excelsior - which finished in second place for the playoffs - won the next two meetings 25-7 and 27-26.
Excelsior has plenty of motivation as it is chasing its first Shield win since 1996.
Valley, a country club formed by the amalgamation of Union and Weston Pirates in the late 1980s, after Union was formed from the amalgamation of Ngapara and Duntroon in 1957.
Old Boys and Excelsior are town clubs formed more than 100 years ago and competition has always been intense.
Maheno, which beat Excelsior 57-7 last weekend, might give the impression that Excelsior is unlikely to be a danger in the semifinals, a belief that will be rejected by Old Boys. After all, Excelsior has beaten Old Boys two of the three times the pair have met this season.
Excelsior, to be fair, will be a stronger side if big midfielders Antonio Misiloi and Taina Tamou take the field. Both are strong defenders and are accomplished with the ball in hand.
Halfback Tarn Crow kicks the goals which give Excelsior confidence, while Tomy Moysey is a more than able first five-eighth.
Excelsior outplayed Old Boys in the loose in their last meeting and once again that battle will be the key. In Samuela Babiau, Matt Duff - who is playing his best rugby for a couple of seasons - and PJ Tili, Excelsior has a trio which can pressure Old Boys.
Old Boys produced rising form after beating Valley last Saturday, with the Old Boys forwards at least matching the vaunted Valley eight.
Last Saturday, Maheno stung Excelsior, producing probably its best performance of the season by scoring nine superlative tries.
If it can perform similarly against Valley, it can win, but expect a rugged forward clash.
Lineout jumper Max Smith, halfback Glen Sturgess and first five-eighth Brad McKenzie will be the brains of the backline.
New midfielder Howard Packman will put pressure on the Maheno defence. He scored two tries against Old Boys last week.
The forward clash between the two sides is going to be a feature. Maheno has a lively pack of forwards led by hooker Hayden Tisdal - a real workhorse at the breakdown - while in lightweight Marcus Balchin, Maheno probably has the most efficient loose forward in the competition.
No 8 Josh Clark's experience and lineout skills will be an advantage to the Maheno side.
If there is to be a "general", it must be halfback Robbie Smith, who has 39 first class games under his belt.
Smith's allround performance against Excelsior last week was superb. His workrate set the example, and his uncanny ability to read the game - especially that of the opposition - put his side on the front foot.
Teenage first five-eighth Ben McCarthy broke his rugby ice on Saturday, while in speedy left winger Adam Johnson, Maheno has a game winner and left winger Fem Bootsan is a good finisher.
- Terry O'Neill