A team including seven players aged 18 and below was pegged back by a Royals side that played most of the game with ten men, with defender Shane Griffin sent off after just seven minutes of play.
Martin Hunter’s side waited until three minutes into the second half to make their man advantage count when skipper Dominic Gape finished from close range after Jake Hesketh’s shot was spilt inside the area.
It looked as though Saints would hold on to secure their first win in six league matches until the Royals mustered the energy to equalise with 12 minutes remaining as midfielder Jack Stacey fired a shot into the ground and into the far corner.
Saints had named striker Sam Gallagher as their lead frontman at the start of the game, supported by Olufela Olomola who, along with Thomas O'Connor, was making his first start for the under-21s side.
Olomola’s and O'Connor’s introductions were two of three changes to the team that lost at Everton a week earlier, with under-18 goalkeeper Harry Lewis also promoted to the starting line-up. 15-year-old Jake Vokins retained his place at left-back.
The visitors gave themselves a mountain to climb when they had defender Griffin sent off after just seven minutes of play. A loose ball in midfield was seized upon by Gallagher, who was brought down by the Royals’ number six to give the referee no choice but to show an early red.
Saints applied the pressure and, soon after the sending off, Vokins struck a free-kick from a position just outside of the area which was well-saved by Stuart Moore in the Royals goal as it arched towards the top corner.
Despite Saints’ numerical advantage, Reading stayed in the game and stuck with their two forwards in attack – both of who had good opportunities to score on 18 minutes. Rowan Liburd robbed Cook of the ball and rounded Lewis outside of his area before finding strike partner Harry Cardwell, but Cook recovered in time to clear the danger.
Reading had another great opportunity a few minutes later as Aaron Kuhl’s corner was headed towards the far post by Conor Shaugnessy, but Richard Bakary was in the right place to clear the ball off the line to keep the game goalless.
After that spell Saints controlled the match until the half-time break, with Gape and Armani Little each going close to breaking the deadlock with well-struck efforts from the edge of the area.
Gape worked Moore from range with a low strike from all of 30 yards out, before Little let fly with a fierce attempt from Olomola’s lay-off that flew narrowly wide inside the last five minutes of the half.
At the start of the second 45, Josh Sims replaced Gallagher in a reshuffle that saw Olomola move into the central position up front.
Within three minutes of the restart Saints took the lead when Hesketh advanced down the left and struck a low shot which Reading ‘keeper Moore could not handle, with home skipper Gape quick to react and tap home from close range.
The goal gave Saints a timely boost in the contest and, with the added impetus of substitute Sims and Olomola also applying pressure through the middle, they caused problems for the visitors.
However, Reading never backed down and, after firing a warning in the 75th minute when skipper Kuhl struck the base of the post from just outside of the area, they levelled the score.
A cross from Sean Long was too high for Alfie Jones and bounced kindly for Stacey, who hit a well-taken strike into the ground to bounce up inside the area and into the back of the net for 1-1.
The leveller invited an open end to the game with both teams looking to win it late on.
Each side created half chances: a last-gasp block from Shaugnessy saved the visitors with Olomola lurking while, at the other end, Sammi Fridjonsson’s first-time effort from a loose clearance after a free-kick cleared the bar.
In the end both sides were good value for their point, with Saints performing well despite their youth and Reading deserving at least a draw given their numerical disadvantage.
Next up for Hunter's side is another home game, as Chelsea visit St Mary's next Monday evening.
Southampton U21s (4-3-2-1): Harry Lewis; Richard Bakary, Ollie Cook, Alfie Jones, Jake Vokins; Dominic Gape (c), Armani Little, Thomas O’Connor; Jake Hesketh, Olufela Olomola; Sam Gallagher (Josh Sims 46). Unused substitutes: Adam Parkes (GK), Yan Valery, Tyreke Johnson, Harley Willard.
Booked: Gape (54), Bakary (86)
Reading U21s (4-3-3): Stuart Moore; Tennai Watson, Shane Griffin, Zac Jules, Sean Long; Conor Shaughnessy, Jack Stacey, Aaron Kuhl (c); Harry Cardwell, Rowan Liburd (Andy Rinomhota 59), Tariqe Fosu (Sami Fridjonsson 73). Unused substitutes: Lewis Ward (GK), Andrija Novakovich.
Booked: Shaughnessy (17), Kuhl (90)
Sent off: Griffin (7)
Referee: Samuel Allison