Manchester City's Antoine Semenyo made it two goals from two games for his new club and Rayan Cherki struck in stoppage time as Pep Guardiola's side beat holders Newcastle United 2-0 away in the first leg of their League Cup semi-final on Tuesday.
Chelsea became the first team into the FA Cup semi-finals when they comfortably beat Championship (second division) Coventry City 2-0 away on Saturday.
Second-tier Forest's buoyant fans were briefly silenced when Leicester grabbed a lifeline before halftime as Kelechi Iheanacho pounced on an error to score from an acute angle.
Chelsea, looking for a league and Cup double, reached the semi-finals of the FA Cup with a 1-0 win over Newcastle United.
Raheem Sterling and Philippe Coutinho helped Liverpool reach the FA Cup fifth round.
East Midlands neighbours Derby County and Nottingham Forest fought out a lively 1-1 draw in an all-Championship (second division) fourth round FA Cup tie at Pride Park on Friday.
Portsmouth reached the FA Cup final for the first time in 69 years after beating West Bromwich Albion 1-0 in the semi-final.
Michael Ballack scored in the 19th minute of extra time to give Chelsea a 2-1 victory over Blackburn Rovers.
Arsenal won 3-1 after extra time at Bolton Wanderers to reach the FA Cup fifth round.
Holders Manchester City will host rivals Manchester United in the FA Cup third round after Sunday's draw threw up a mouth-watering derby.
Liverpool beat Cardiff City side 3-1 in the FA Cup on Sunday
Discarded striker Danny Welbeck returned to demolish Manchester United's hopes of silverware by netting the winner in Arsenal's 2-1 FA Cup quarter-final victory at Old Trafford on Monday.
Tottenham Hotspur's Son Heung-min returned to form with two goals in his side's 3-0 defeat of second-tier Preston North End in the FA Cup fourth round and Casemiro also grabbed a brace in Manchester United's 3-1 win over Reading.
Manchester City defender Nathan Ake struck in the second half to earn a hard-fought 1-0 victory over visitors Arsenal in the FA Cup fourth round on Friday.
Arsenal manager Mikel Arteta called on his players to "live in the present" ahead of Sunday's visit to local rivals Tottenham Hotspur in a battle to stay ahead in the title race after their lead was cut short by successive Premier League draws.
Liverpool were left frustrated by Championship side Blackburn Rovers who defended heroically to draw 0-0 at Anfield.
Teams progressing to the latter stages of the FA Cup next season will be allowed to field a fourth substitute in extra time, the English Football Association (FA) announced on Wednesday.
Holders Chelsea beat Aston Villa 3-0 to sweep into the FA Cup final for the third time in four seasons on Saturday and keep alive their dream of a first FA Cup and League double. All three goals came late in the game with Didier Drogba breaking Villa's resistance after 67 minutes before Florent Malouda (89th) and Frank Lampard, deep in stoppage time, gave Chelsea an ultimately comfortable victory.
Holders Chelsea eased into the quarter-finals of the FA Cup with a straightforward 4-1 home victory over Championship (second division) promotion challengers Cardiff City on Saturday.
Manchester City's 35-year wait for a trophy ended when Yaya Toure's unstoppable shot sealed a deserved 1-0 win over Stoke City in the FA Cup final on Saturday.
Stoke City reached the FA Cup final for the first time when three goals in the first 30 minutes paved the way to a stunning 5-0 win over Bolton Wanderers at Wembley Stadium on Sunday.
Liverpool suffered a shock 2-1 loss to Championship side Wolverhampton Wanderers in the FA Cup fourth round on Saturday, handing manager Juergen Klopp a third home defeat in a row.
Everton knocked holders Chelsea out of the FA Cup when they won their fourth-round replay 4-3 on penalties after a 1-1 draw at Stamford Bridge on Saturday.
Everton skipper Phil Neville scored the decisive spot-kick to give his side a 4-3 penalty shoot-out win over holders Chelsea after their FA Cup fourth-round replay ended in a 1-1 draw after extra-time at Stamford Bridge on Saturday.
Arsenal suffered a second humiliation in two months against lower league opponents when Blackburn Rovers beat them 1-0 in the fifth round of the FA Cup on Saturday.
Stephane Sessegnon struck deep into extra-time as Sunderland booked their place in the FA Cup fifth round with a 2-1 replay win over second-tier rivals Middlesbrough on Wednesday.
Images from Saturday's third round matches in the FA Cup.
Third-tier Oldham Athletic stunned seven-times FA Cup winners Liverpool with a shock 3-2 fourth-round win on Sunday and Leeds United caused another big upset by knocking out Tottenham Hotspur 2-1 at Elland Road.
Everton enjoyed trouble-free progress to the FA Cup fourth round with a 5-1 victory at fourth tier Cheltenham Town on Monday.
After bagging the League Cup, being locked in a titanic battle with Liverpool for the Premier League title and in the Champions League quarter-finals, Pep Guardiola's side remain on course for an unprecedented clean sweep.
Arsenal set up an FA Cup quarter-final against Hull City when they cruised past Championship (second division) side Burnley 3-0 in their delayed fifth round match at the Emirates Stadium on Sunday.
City dominated the early exchanges, pinning Arsenal back, but were stopped in their tracks when Aubameyang produced a neat finish in the 19th minute following a flowing end-to-end move.
First-half goals by Romelu Lukaku and Hakim Ziyech knocked the stuffing out of second-tier Middlesbrough, who had eliminated Manchester United and Tottenham Hotspur in previous rounds.
Shorn of European excitement and with only a remote hope of winning the Premier League, Manchester United manager Louis Van Gaal wants the FA Cup to garnish his first season in charge.
The Gunners will take on Manchester United at Old Trafford in the FA Cup fifth round.
Juergen Klopp's side will meet the winners of Sunday's other semi-final between Chelsea and Crystal Palace in the May 14th final
Arsenal beat City 2-1 in extra time to book a place in the final against Chelsea on May 27 and their progress is in contrast to the Premier League season that could see them miss out on a Champions League spot for the first time under Wenger.
Holders and FA Cup favourites Chelsea were handed a home tie against Cardiff City when the fifth-round draw was made on Sunday.