All of a sudden, Fantasy Premier League managers have hit something of a crossroads ahead of Gameweek Four thanks to a prime opportunity to back Chelsea’s star attackers.Joao Pedro (£7.7m), Cole Palmer (£9.6m) and Morgan Rogers (£7.6m) have all started the season in fine form and the west Londoners face Hull City at Stamford Bridge on the same weekend that Manchester City and Manchester United’s prime FPL options will face each other in the Manchester derby at Old Trafford.So, is it time to rip up our sides to invest in Chelsea players, potentially at the expense of pricey assets from the two Manchester clubs, or should we be more conservative with our transfer plans?Why it makes sense to consider Chelsea stars in Gameweek FourThe argument for investing in Chelsea players is incredibly strong, especially since they have scored eight goals in their opening three games.At the heart of the action has been their front three of Joao Pedro (£7.7m), Cole Palmer (£9.6m) and Morgan Rogers (£7.6m). This trio have scored six of their team’s eight goals and have also produced three direct goal-and-assist combinations.They are a formidable threat, with Joao Pedro and Palmer level on fantasy points (21), and Rogers (19) just two points adrift of them.Chelsea rank sixth for big chances on goal with 10, while they have outperformed their expected goals total, with an xG of exactly six.Palmer is top among midfielders for shots on target (five) and shots in the box (nine), while Rogers leads the way among all players for key passes with 10.Joao Pedro has a leading four goal involvements for the campaign and is the most owned player in the game at the time of writing. It feels like adding a second Chelsea attacker as a minimum is the way to go.Joao Pedro is FPL’s most-selected player (Justin Setterfield/Getty Images)Rogers is more popular than Palmer, potentially due to the £2million difference in price, making the former easier to fit into our squads.Palmer, however, has been Chelsea’s main penalty taker in recent seasons. New manager Xabi Alonso stated prior to the season he would be he making his own decision on who his number one taker would be, yet his star attacking midfielder has an enviable record from the spot, scoring 24 of his 26 career penalties, including one in their 6-3 win over Leeds in the Carabao Cup on Wednesday night. Palmer has failed to convert on two occasions in a Chelsea shirt, once in each of his last two seasons.In that cup win over Leeds, Palmer scored twice while Rogers, who also came off the bench at half-time, got three assists (he thought he had four but his cross for Valentin Barco got a touch off Leeds goalkeeper Michael Zetterer), which will only add to their appeal.Is Hull’s defensive solidity sustainable?It is clear that Chelsea’s attack have begun the season in fine form, with the potential to be one of the most prolific in the Premier League this season.However, we do also need to be aware that their opponents Hull City have also got off to a flying start, especially when it comes to their defensive prowess.They are unbeaten in the league to date, with two wins and a draw, with their first victory coming on the opening day of the season against Manchester United. Crucially, they’ve also kept three clean sheets.Despite being knocked out of the Carabao Cup by Sunderland in midweek, they are the only side in the Premier League who are yet to concede a goal in this campaign, with their defenders Semi Ajayi (£4.1m), Nobel Mendy (£4.0m) and John Egan (£4.1m) the highest scoring in the game.They rank third for big chances conceded on their goal (five), behind Arsenal and Nottingham Forest.However, the underlying numbers may indicate some overperformance, with 5.05 expected goals conceded. Only five sides have conceded more than their 45 shots.Chelsea will be aware of Hull City’s defensive record going into this game and could easily become frustrated if they don’t take their opportunities early in the game.Hull City have yet to concede a goal in the Premier League this season (Molly Darlington/Getty Images)Who are the key players to sell?My biggest challenge is finding a route to a Chelsea midfielder without either using lots of transfers to shift funds around or selling a premium pick.I simply refuse to drop Manchester United’s Bruno Fernandes (£12.0m) ahead of the Manchester derby, with the midfielder racking up four goal involvements already this campaign.Michael Carrick’s side have been so consistent at Old Trafford under his tenure, with just one defeat in the Premier League.Crucially, when Manchester City visited back in January, Manchester United were the 2-0 victors, with Fernandes getting a double-digit haul. In 10 Premier League games under Carrick at Old Trafford, Fernandes has never blanked, with six double digit-hauls along the wayI’d also be cautious of selling Bryan Mbeumo (£7.9m) to fund a move for a Chelsea midfielder too. He has produced two goals and an assist this season, and he scored the last time these two sides met.I think it’s easier to sell a Manchester City midfielder around this price point, with rotation hitting in recent games.Rayan Cherki (£7.8m) is prone to early substitutions while Antoine Semenyo (£8.4m) had a poor performance in the Champions League in midweek.New recruit Iliman Ndiaye (£5.9m) will share minutes with Phil Foden (£7.0m), who found himself on the bench against Coventry City in Gameweek 3.It’s becoming increasingly clear that Erling Haaland (£15.5m) is perhaps enough when it comes to investment in Manchester City’s attack.Why the Free Hit strategy is appealingOne route to maximising on Chelsea assets this week and avoiding the Manchester derby is to play the Free Hit chip — and it’s a strategy I think is viable.If you own at least four assets from the Manchester derby, and perhaps only Joao Pedro from Chelsea, then the argument becomes more convincing.That’s not the only fixture to target either, with Liverpool hosting a leaky Fulham defence and Arsenal travelling to Sunderland. There’s potential to go as far as tripling up on Arsenal’s defence and Liverpool’s attack among these fixtures.The only reason I’m not on this strategy is that I feel like given my squad structure, particularly after playing the Bench Boost in Gameweek 1, that I’m not too far away using my wildcard.On a personal level, playing the Free Hit and wildcard in close proximity doesn’t feel like the smart play and limits flexibility going forward. It could make sense for other FPL managers, though.