VIDEO HIGHLIGHTS: (4-0) Chelsea Vs Brentford, All goals, FA Cup
Chelsea broke Brentford's resistance with a potent second-half attacking display to eliminate the third-tier club from the FA Cup at the second attempt with a 4-0 victory, while Manchester City crushed Leeds by the same score.
Held by Brentford three weeks ago, defending champion Chelsea couldn't find a breakthrough until the 54th minute of the fourth-round replay when Juan Mata struck from the edge of the penalty area.
Oscar found the net for the second time in four days, Frank Lampard side-footed in his 199th goal for the club, and captain John Terry completed the 4-0 thrashing with a header.
"They made it very difficult," Terry said. "(They had) two banks of four and sat very deep."
Chelsea will play at Middlesbrough on February 27 in the fifth round. Man City is already through to the quarterfinals after beating second-tier club Leeds.
Yaya Toure put the Premier League champions ahead after five minutes before Sergio Aguero scored from the penalty spot, helped to set up Carlos Tevez's close-range goal after the break and then collected his second off the post.
"It was important we bounced back," City midfielder James Milner said. "They've knocked a few Premier League teams out of cups this season, so it was important we did a job and we did it well. We had to improve on last week, we did that."
In Sunday's (UKt) late cup match, Wigan was at Huddersfield, while Liverpool routed Swansea 5-0 in the only Premier League fixture of the weekend.
The cup shocks of the weekend came on Saturday with second-tier club Blackburn winning at Arsenal and third-tier team Oldham drawing with Everton.
Just how lucrative a cup run can be to lower-league teams was highlighted by Brentford estimating that it has earned more than $1 million from the two fourth-round matches against Chelsea.
The seventh-place team in League One - a point behind the playoff places - managed to repel waves of attacks by Chelsea with a disciplined display in the first half.
The visitors even found the net just before half time through Marcello Trotta, but the referee had already blown for a foul on Brentford midfielder Adam Forshaw.
Chelsea's finishing was wayward in the first half, although Oscar did hit the post. After the break, the intensity was raised - and Brentford paid the price.
Goalkeeper Petr Cech launched the ball forward, Demba Ba held off the Brentford defense, and Mata picked up possession before crisply striking into the net.
The second was even slicker from Oscar in the 68th.
Eden Hazard, who had just replaced Victor Moses, seized possession near the halfway line and powered into the penalty area where he sent the ball to Branislav Ivanovic. The right back cut the ball back to Oscar, who flicked it into the net through three defenders.
After the struggle scoring in the first half, Chelsea took just three further minutes to make it 3-0. Mata broke down the left flank and squared the ball for an unmarked Lampard to volley into the net.
The 34-year-old midfielder's 199th goal puts him three behind Bobby Tambling's club record, however he hasn't been offered a new contract beyond the end of the season - much to the annoyance of Chelsea fans.
Another member of Chelsea's old guard found the net in the 82nd, with Terry meeting Oscar's cross with a header.
At Etihad Stadium, a City win seemed certain from the fifth minute after neat link-up play between David Silva, Tevez and Yaya Toure led to the latter rounding goalkeeper Jamie Ashdown and scoring.
Ten minutes later, Aguero was on target from the spot after the Argentina striker had tangled with Tom Lees.
Aguero provided the cross seven minutes after the break that Tevez tapped in at the far post. And Aguero found the net again in the 74th after latching onto Silva's high, defense-splitting pass, and curling past Ashdown off the post.
At Anfield, the League Cup was on Swansea's minds as several key players, including top-scorer Michu, were left on the bench ahead of next Sunday's final against Bradford.
The weakened side collapsed after Steven Gerrard's spot kick beat goalkeeper Michael Vorm in the 34th minute after Luis Suarez was fouled by Kemy Agustien.
Just 16 seconds into the second half, Phillippe Coutinho marked his debut by going through the Swansea defense before beating Vorm.
Inside five minutes, Liverpool was further ahead after Jose Enrique poked the ball into the net from Daniel Sturridge's pass.
Suarez went through past the Swansea center backs before firing in the fourth and, after Wayne Routledge handled, Sturridge netted Liverpool's second penalty in the 71st.