Gylfi Sigurdsson says Everton must "work hard" to build on their run of three straight wins and launch a sustained assault on the Premier League's top four positions. 

Thursday's 1-0 victory at West Bromwich Albion - a result that followed a 2-0 Merseyside derby win at Anfield and single-goal defeat of Southampton - temporarily moved the Blues up to fourth in the table with 12 games remaining. Chelsea's victory at Liverpool later in the evening dropped Everton to fifth.  

Carlo Ancelotti's side trail second-placed Manchester United by five points and Leicester City in third by four but have a game in hand over both. 

Sigurdsson stepped off the bench at The Hawthorns and within a minute had fired in the delivery from which Richarlison headed his second match-winning goal in four days. 

The triumph was also a ninth on the road this term for the Toffees, who travel to fellow European contenders Chelsea on Monday night. 

Asked if Everton's players believe they can push for a top-four finish, Sigurdsson said: "We're obviously confident. 

"It's a couple of good results in a row now for us but it's very tight at the top and down to the middle of the table. 

"We've just got to keep going, work hard and get on a run for the next five or six weeks.

"If we can do that, we've got a good chance."

Richarlison's goal took him to 12 for the season, however the Brazilian has now struck in each of his past four games. 

Add a brace in the Blues' 5-4 FA Cup win over Tottenham Hotspur on 10 February and the 23-year-old has six in six outings for the Blues. 

With Everton looking to secure European qualification for the first time in four years, Sigurdsson believes his teammate has hit peak form at just the right time. 

"He's very important," he said. "Obviously, Dominic [Calvert-Lewin] has scored a lot of goals and brings a lot to the team but Richy is obviously chipping in with the goals at the moment and at the right time. 

"He nicked a 1-0 in the last game and 1-0 today so he's got us six points in two games. 

"It was obviously a tough game. We knew they were going to defend deep and defend well so we had idea that it might be a set piece that would win the game.

"It was obviously very important to get that goal."