Strand-Young, a senior guard, found Ameer Staggs for the go-ahead layup. Strand-Young stole the ensuing inbounds pass but missed the front end of a one-and-one. Upper Darby's attempt fell short at the buzzer.
Ridley did not take its first lead until Brett Foster's three-pointer with a minute left. He scored 10 of his game-high 15 points in the fourth quarter.
Staggs was strong on the post and was aided by Pat O'Neill.
In other Central League action:
Brian Allen (14 points and five assists) led visiting Radnor over Springfield (Delco), 56-51. Kevin McCormick added 13 points and six rebounds.
Andrew Diehl scored 17 points to lead Conestoga past host Garnet Valley, 60-45.
Suburban One. Avery Nyekan scored 15 points and Brian Kilcoyne added nine to lead Bensalem over visiting Council Rock North, 39-30.
Matt Penecale scored eight of his 12 points in the second half to help Abington turn away visiting William Tennent, 62-50. Senior guard Anthony Lee added 10 points and six assists.
Chris Vila scored eight of his game-high 19 points in the third quarter, and Wissahickon cruised past visiting Upper Merion, 67-38.
Joe Molettiere scored 24 points, and Pennridge rolled at Souderton, 58-39.
Bryce Dobisch poured in 18 points and Matt Scamuffo added 14 to lead host Central Bucks South past Central Bucks West, 44-40.
Jimmy Murray scored 28 points, and Plymouth Whitemarsh pulled away from host Norristown, 67-42.
Senior guard Arron Burton scored nine of his 22 points in the second quarter, and Cheltenham topped visiting Upper Moreland, 52-41.
Catholic. Senior forward Jamal Custis scored 13 of his game-high 21 points in the first half as Neumann-Goretti eased past visiting La Salle, 82-58.
Ja'Quan Newton added 19 points, Lamarr Kimble grabbed seven rebounds, Tony Toplyn had four blocks, and Troy Harper had four steals for the Saints.
Inter-Ac. Eighth grader Cameron Reddish scored 10 points as the Haverford School rolled past visiting Springside Chestnut Hill, 65-37. The 6-3 guard grabbed nine rebounds.
Public. Sankofa Freedom's Anthony Wright-Downing scored his 1,000th career point in the second quarter of the host Warriors' 63-52 win over Franklin Learning Center. The senior guard scored 18 points and is the school's all-time leader in career points with 1,010.
Jaekwon Carlyle scored 11 points and hit a pair of free throws with 3.9 seconds left to seal Imhotep Charter's 69-66 win over visiting Philadelphia Electrical.
Terquin Mott, a sophomore forward, put in seven of his 19 points in the third quarter, and host Math, Civics & Sciences pulled away from Frankford, 63-58. Mike Watkins added 13 rebounds and seven blocks.
Sophomore point guard Jabbar Shy stripped the ball handler and ran in for a layup with 20 seconds left to carry West Philadelphia over Olney, 63-62. Lamar Strand added 10 assists, and Tyquaan Bardlavens had 10 rebounds.
McDonald's All-American Game. Neumann-Goretti's Ja'Quan Newton and five other area boys' basketball players were nominated for the McDonald's All-American Game.
Joining Newton were Great Valley's Mikal Bridges, Roman Catholic's Shep Garner, Math, Civics and Sciences' Lou Myers, and Lansdale Catholic's Brian Rafferty and Andrew Riviello.
The final rosters will be announced on Jan. 29, and the game will be played April 2 in Chicago.