Luis Suarez marked his 100th cap with the winner as Uruguay qualified for the World Cup knockout stages with an unconvincing victory which eliminated opponents Saudi Arabia.
Barcelona striker Suarez volleyed home from a corner midway through the first half as Oscar Tabarez's side laboured to a 1-0 win in Rostov-on-Don.
The result means hosts Russia, who also won their two opening Group A games, will join Uruguay in the last 16, while pointless Egypt and Saudi Arabia make an early exit.
Saudi Arabia, thrashed 5-0 by Russia in the opening game of the tournament, were playing South American opposition at a World Cup for the first time.
They started with some promise but fell behind with 23 minutes played following an error from goalkeeper Mohmmed Al Owais.
Al Owais, one of four men brought in by coach Juan Antonio Pizzi following the opening loss to Russia, misjudged an inswinging corner from the left, allowing Suarez a simple finish into the unguarded net.
It was Suarez' 52nd goal for his country as he became the first Uruguayan to score at three World Cups.
Despite taking the lead, Uruguay were far from impressive and goalkeeper Fernando Muslera had to be alert to tip over a dipping effort from Hattan Bahebri.
Suarez threatened with a free-kick which was theatrically repelled by Al Owais early in the second period, before Carlos Sanchez wasted a free header following a fine cross from Edinson Cavani.
Paris St Germain striker Cavani almost doubled the lead with 11 minutes remaining when his attempt to divert home Cristian Rodriguez's speculative effort flashed narrowly wide with Al Owais wrong-footed.
Saudi Arabia collapsed in their opener against the Russians, losing 5-0, but they managed to keep the scoreline respectable here, albeit rarely threatening to snatch an unlikely draw.
Yasser Al-Shahrani attempted to prevent their early exit in stoppage time but his deflected drive from distance was comfortably collected by Muslera.
Uruguay's victory means long-serving coach Tabarez has guided them out of the World Cup group stages in three successive tournaments.
They meet Russia on Monday in Samara to decide who will top the group, while the Green Falcons will take on neighbours Egypt at the same time hoping to score their first goal of the tournament and avoid finishing bottom.