Three years to the day after facing Yeovil in League One, Saints' impressive rise was highlighted by the fact seven of the starting line-up at Selhurst Park were away on international duty during the week.
Rodriguez was one of four called up for England's friendly against Denmark and struck the decisive blow on his return to club duty, with his first-half goal enough to secure a 1-0 win.
The 24-year-old, restricted to a watching brief at Wembley, brought a dull match to life in the 37th minute, latching onto a weak header by former Southampton winger Jason Puncheon and then beating Julian Speroni in a 50-50 challenge to finish into an open goal.
Saints came close to adding to Rodriguez's eighth away league goal of the season as half-time approached, with fellow England international Rickie Lambert hitting the base of the post.
Palace felt aggrieved that Dejan Lovren avoided a red card for what some deemed a last-man challenge on Yannick Bolasie early in the second half - a decision that helped Saints end a three-match losing streak in all competitions and deny Tony Pulis' side the chance to edge further from the drop zone.
The match began slowly with Rodriguez and a weak Glenn Murray penalty appeal the only moments of note until the ninth minute, when Speroni produced a wonderful save to deny Steven Davis - unaware the offside flag had been raised.
It was one of few clear-cut chances created by Southampton in a frustrating opening 30 minutes, with diligent Palace defending meaning their possession counted for nothing.
Murray and Rodriguez had efforts blocked in that period, before Jack Cork's match was ended prematurely.
The midfielder landed awkwardly on his ankle when clearing the ball, leading to Victor Wanyama's 34th-minute introduction.
Perhaps destabilised by the enforced change, Saints were forced onto the back foot as Palace enjoyed a spell in the ascendancy.
The hosts had a flurry of corners in quick succession, but the third ended with them falling behind.
With the set-piece hoofed away, Puncheon's attempted header back to Dean Moxey was weak and intercepted by Rodriguez, who won a challenge with Speroni and managed to slot into the empty goal as he fell on his rear.
It was an unorthodox goal and a mistake Puncheon attempted to immediately atone for, only for his fine cross to be met by a wayward Bolasie effort.
The pacy winger did better by stinging the palms of Artur Boruc in first-half stoppage time, but it was Southampton that went in at the break on top.
Davis threatened and Luke Shaw - fresh from his England debut - stung the palms of Speroni either side of a fine effort from Lambert, who made the most of Palace's inability to clear an Adam Lallana cross and flicked the ball with the outside of his right foot onto the post.
Palace attempted to make amends for the visitors' missed opportunities as they returned for the second half rejuvenated.
Bolasie was proving a handful and, having darted past two Saints players, was brought down by a poor Lovren tackle when through on goal.
The Palace fans called for the Croatia international to be sent off, but Howard Webb did not deem him the last man so only produced a yellow card.
Lovren joined fellow centre-back Fonte in the referee's notebook, which soon also included Davis and Palace captain Mile Jedinak as tempers began to fray.
The latter's foul allowed Lambert to come close with a 25-yard free-kick, which came shortly after Murray saw penalty appeals waved away at the other end.
Schneiderlin was booked for a lunge on Jedinak as the visitors looked to maintain their lead, with Nathaniel Clyne, making his first appearance at Selhurst Park since leaving Palace, clearing a dangerous cross from substitute Cameron Jerome.
Lovren hacked away a Joe Ledley cross as Jerome loitered with intent and Shaw tested Speroni as the match entered the final 15 minutes.
Palace desperately search for a leveller but, aside from Boruc gathering a looping header from the offside Jerome and Clyne being booked, there was little to report as Saints held firm.